As I described then, tools were serving no purpose that was separate from skills. That's now come back here, and the problem is amplified because there are so many more tool proficiencies. Instead of proficiencies (mounts), re-introduce the riding skill; instead of thieves' tools, re-introduce disable device. Just because a skill requires the use of certain equipment (a horse, a lockpick, climbing gear), does not mean that there should be a bonus from that equipment.
In brief: Replace most tool proficiencies with a skill, and use the skill system.
Tool profs and skills are in fact so similar that they could be the same.
IMO the reason why they changed Riding to a tool proficiency, is because they want to expand it to cover unusual mounts, without making them automatic. Classes granting this skill actually grant "Mounts (land)", suggesting there can be also proficiency in water mounts, flying mounts and maybe something else. I think it sounds very good that unusual mounts aren't automatic but require specific proficiency.
In brief: all classes should give 1 skill only, and rogues should have a second background.
Uhm... but then if you dip into 1 level of Rogue, you get the bonus background. To prevent that, we would need an ad-hoc rule in the multiclassing rules specifically mentioning this case. It's easier to just have a general rule that e.g. "you only gain one skill" (or "you gain no skills") when taking a level in a new class.
Also, it doesn't feel very appropriate to me
narratively to have two backgrounds.
There's a general problem here with skills, that characters like Ranger and Rogue are skillful, and that's a
defining feature. They are expected to be so, which makes it odd to start levelling up in one of these as your 2nd class, and don't get all their skills. OTOH, if we just stack skills from different classes, we can get heavy multiclasses to have too many skills compared to anybody else. This was a non-existing problem in 3e because of how skill points worked, but now we're settled with level-based bonuses, so they have to find a different solution for multiclassed characters.
Save proficiencies are a problem, because they are going to be so useful, especially at higher levels. Perhaps should be limited to one-extra save proficiency if you multiclass, not (usually) two.
Yes, this is what I suggested also. Max 1, or even none.
What you want creates an ugly problem, All fighters would have to be soldiers or they would be completely useless as fighters, because a scholarly fighter wouldn't be proficient with even his own fists and wouldn't be able to wear any kind of armor. A mage soldier on the other hand would be broken, casting iin heay armor and using all weapons with proficiency, esentially one shoting the so called fighter who wouldn't be able to evne use armor to protect himself
I agree with you, weapon/armor are used primarily in adventures (Soldier can be an exception) not in civilian life which is what backgrounds represent, so it makes a lot more sense for weapon/armor proficiencies to come from classes.
Furthermore, let's keep in mind that backgrounds are a tool to create interesting character concepts/variations, but at the same time it is quite expected that the majority of players will choose a background that matches with the class, at least for their first PCs. Fighter+Soldier, Cleric+Priest, Rogue+GuildThief and Mage+Sage (and also Bard+Minstrel and Ranger+Guide) will be the most commonly seen, so we can't afford these to be inferior.
Save proficiencies seem such an issue for me - as [MENTION=69074]Cyberen[/MENTION] has noted - that I feel they need to be revisited altogether.
I was convinced months ago that we could just have no scaling spells DC and no scaling ST at all, but most gamers want them both to scale, so I gave up.
I don't think the problem is the magnitude, I think we can use the same rules of +1 to +6 as all other proficiencies.
Instead, I think the problem is that spellcasters (but not monsters) have freedom in choosing spells appropriate to the target, i.e. casting a Dex-ST spell against a target that presumably is weak in Dex-ST.
But overall I think the rules for proficiencies, spells DC and ST are pretty solid as long as single-class PCs are involved,
and start to fall apart with heavy multiclassing (e.g. 3 or more classes). Rather than throwing away all the design job and good results so far, I'd focus on multiclassing rules and restrictions to prevent abusive combos.