Its true that a wizard gets a few more spells per day than a Bard, but in comparing old editions Bards still come out much better.
- Bards get access to the next tier of spells at the same time as other classes, ensuring they are always on the power curve.
- Bard save DCs are not weakened by lower spell levels (a problem in 3e). Bard spell DCs are as good as anyone else.
- Bards have a full caster level "equivalent", in some iterations bards have had more limited caster levels.
Wizards get a few more spells prepped than bards know (plus the benefits of swapping them), carry more rituals than bards learn because of a better ritual caster mechanic, have an extra cantrip, and add anywhere from one to ten spell levels worth of extra slots in a day before looking at spell mastery or the fact that wizard traditions enhance spellcasting.
The only advantage a bard has is access to spells not available to the wizard spell list but after that the wizard is better at spell casting in every way.
Bards get access to the next tier of spells at the same time as other classes, ensuring they are always on the power curve.
Sometimes yes, sometimes no.
Adding spells to the classes at different spell levels for each class was an awkward mechanic and not restricted to bards. It was a method of giving bards spells from a higher band at roughly the same time, however.
A bard or wizard would cast
charm monster at 7th level and the difference was 5% of the rolls made for the bard spell would be saved that the wizard spell would fail, and 95% of the time it was the same effect at the same level.
I would also point out that sorcerers also had delayed spell levels.
Bard save DCs are not weakened by lower spell levels (a problem in 3e). Bard spell DCs are as good as anyone else.
The power curve from the next tier of spells is not looking at the big picture. 3.5 bards used songs to a greater extent as additional magical power than 5e bards use inspiration dice. All classes have differences, however, such as giving wizards access to better cantrip use and rituals and more hit points and hit dice healing when looking at 3.5 wizards. And things that are not as good.
What's important to keep in mind is that a comparison between 3.x bards and 5e bards isn't relevant to comparing bards and wizards. 3.5 bards get compared to 3.5 wizards while 5e bards get compared to 5e wizards. The point I was bringing up was that bards were grouped with full casters in the mechanics even if they were not always quite as good.
Getting to the DC's, 1e and 2e used a different DC mechanic so that wasn't true in those editions and it's wasn't true in 4e. 5e being the same as other casters matches most editions. 3.5 is a bit misleading because the DC being based on spell level was a thing, but the majority of spells would have had the exact same DC from spell levels 1 thru 6, and
fascinate was based on a CHA skill. At 1st level using average dice on rolling gave a 1st level spell a 13 DC and pushing 18 in a point buy maxed that at 15 DC.
Fascinate at 1st level used a perform check for a range from 7 (min roll 1 + 4 ranks +2 ability score) to 26 (max roll 20 +4 ranks +2 ability score) with an average of 16 DC. Add 2 to each of those pushing CHA on point buy.
By 20th level a 9th level spell would be 19 DC plus modifiers and
fascinate would range from 24 DC to 43 DC (plus bonuses) with an average of 33 DC plus bonuses.
Other SLA's (spell-like abilities) such as
suggestion used a class level mechanic of 10 + 1/2 class level plus ability score.
Suggestion started at 13 DC + CHA mod and ended at 20 DC plus CHA mod.
Only a few higher level spell level slots beat the bard spell level slots where the spell levels 1-6 were the same, song SLA's were similar DC's to the higher level slots, and
fascinate DC's blew wizard DC's away. And then I could just use
sublime chord to also have up to 9th level spells and invalidate the DC argument even more. The difference was clerics, druids, sorcerers, and wizards had a better variety of spells at those high DC's, not that the DC's weren't there. Song SLA's (spell-like abilities) were
higher DC's than spell DC's.
Bards have a full caster level "equivalent", in some iterations bards have had more limited caster levels.
That's misleading.
The original bard used weapons like a fighter but had some armor restrictions, attacked and saved as a cleric, had a similarity to the original clerics in not getting spells until 2nd level but used MU spells, had thief skills at 1/2 level, and had innate charm and lore abilities. Caster level was unaffected and they cast spells at the class level like other spell casters.
In 1e there were two (optional) versions of bards. The PHB appendix bard had caster level restriction of 12th level and later 13th level but that's based on the druid having a max 14th class level that required fighting from the limited pool of higher level druids at 12th level.
The other optional version was the dragon magazine bard. That bard used fighter attack progression but did not gain multiple attacks, a combined saving throw table for clerics and wizards, and also started casting spells at 2nd level like the original bards and clerics. This bard cast druid spells at 1 level below their bard class level. This bard also cast illusionist spells at 3 levels below bard class level. That made for a unique situation where the bard would end up casting druid spells at a higher caster level than druids (because of XP advancement and fight club rules) and lower level than illusionist.
Paladins and rangers had odd restrictions because RAW they started casting spells at the caster level they got the spells and that was recommended to be house-ruled to a level subtraction from Dragon Magazine but was not errata'd. It led to 1e rangers and paladins casting spells at a higher caster level than druids or bards until Unearthed Arcana increased the maximum class level for druids and the Dragon Magazine remake of the bard came out. At that point paladins capped at 20th caster level and rangers capped at 17th caster level while appendix bards capped at 13th caster level and DrgMag bards only took the tiny level restriction. Regardless of the bard being used, bards had more spell slots than paladins and rangers combined.
2e bards continued to wait until 2nd level for spells but they used a spell book and followed the rules for wizards when it came to spell casting. Paladins and rangers had the house-rule for caster level made official and started casting as a 1st level caster when they received spells, then capped out at 9th level casters.
A key point here is bards used full caster level but they used rogue experience advancement and had bonuses for everything. That lead to being 1-2 levels above other spell casters and the caster level
rules had bards casting spells at a higher caster level because of the experience rules. For example, bards hit 3rd level when wizards hit 2nd level.
In both editions, rangers started gaining spells at 8th level and paladins started gaining spells at 9th level. In 2e bards wrecked on caster level, had more slots than paladins and rangers combined, and still cast spell levels up to a similar level as clerics and druids.
3rd edition bards are the odd exception, not the typical example. 1e, 2e, 4e, and now 5e bards were/are very close to clerics and druids in spellcasting (realistically the high WIS req for 6th and 7th level spells in the first two editions limited clerics and druids to 5th-level spells unless lucky rolling or DM facilitation occured). 3e was an attempt to split spells and songs apart but still made for a spell caster as I pointed out.
Keeping on point for caster level, bards in 3.x used the class level for the caster level, just like clerics, druids, sorcerers, and wizards. 0-level spells were added to the system and bard were spellcasters with a caster level right from 1st level, relying on cantrips and songs at that level. Spell progression was slower but spell + song progression is the point on the split system.
In 3e, bards had no caster level restrictions. Paladins and rangers cast spells as if they were one-half their level.
The image above demonstrates the 3.5 casting classes. I added
wildshape for the druid, songs for the bard, and specialization for the wizard. I gave a bonus slot for spell levels 1-4 for an assumed casting stat and a bonus spell slot for level 1-2 for rangers and paladins based on more of a martial focus. Feats and ASI's might alter those a bit but it's a good representation. There's an argument for LOH's value added to the paladin but it's still not going to reach the bard's level of magical abilities.
That's also without subclass bonuses.
Number of magical actions were easily far closer to other spellcasters than to what we consider half-casters now, caster level was equal to the other caster levels instead of the half-casters, and the DC's were a lot more similar to the other spell casters instead of the half-casters. If we build a new system and we're making an easy multiclassing approve for the spell tables then we have a choice for grouping the bard one way or the other. The bard clearly groups with the full casters even looking at 3e, the only edition where all other major spell casters had those higher level spell slots.
Bards fit in to that higher grouping in all editions. The only caster level restrictions were from an edition where they were options outside of the core classes and that changed with the first edition in which they were included with that group.