Can someone help me out with this? I'm new to 4th. Is the game so balanced that these collections of +1s are *ncessary* for the game to work well? I ran years of 3.5 with a group that couldn't give a fig about optimization, and we never had any problems. Is it really the case in 4 that if you don't spend your 1st 4 feats on dull bonuses to fix math, you're doomed to mediocrity?
Well, yes and no.
You won't start really noticing anything significant until about starting Paragon or level 11.
So if the PCs never get to level 11, then you'll probably never notice it.
But at level 11, the difference is +2 to hit. That starts becoming noticable and it becomes pretty large at level 21 and +3 to hit.
You'll also not notice it too much if you play a melee PC using a +3 proficiency weapon. Such PCs are relatively speaking, ~+1 to hit over implement users. They can also charge for +1 more and can sometimes get +2 for flank or prone easier than implement users. And some melee classes have some type of weapon training for +1, or can take a Paragon Path with another +1 bonus to hit.
So if you don't want to worry about Expertise at all, playing certain types of melee PCs with a +3 proficient weapon can get you all of the way to level 30 without having to worry about Expertise.
But Expertise is, in my opinion, eventually absolutely required for implement users. If you have most PCs taking Expertise and your implement user not doing so, then you can run into situations where the Fighter at level one is +9 with +3 prof, +1 weapon training, +1 Expertise, 18 Str and your Wizard is +4 with 18 Int. The Fighter is hitting AC 15 (even without charge or flank) on a 6 and the Wizard is hitting Will 13 on a 9. Players will pick up on that right away.
With regard to defenses, the main one where it matters is the PC's lowest NAD (non-AC defense, i.e. will, reflex, or fort). Most players bump up the same two ability scores throughout the lifetime of the PC. This means that the third one suffers.
Say you have a PC with a 11 starting Reflex which is about as low as it gets, but 10 is not impossible. If this defense is not boosted, then in 29 levels (i.e. level 30), the monsters are +29 to hit whereas the defense will only go up by +15 level, +6 magic neck item, +1 ability scores = +22. The monsters will be at +7 to hit compared to level one. What's worse is that the same level monsters at level one already hit on a 7 (+4 vs. 11), so now they hit on a 2.
And, the ability score requirements may limit the player anyway. Say the PC has a starting Reflex of 13. The player cannot take Superior Reflexes for the PC until level 21. That's 2/3rds of the entire potential lifetime of the PC with a really low defense. The player is almost required to take Improved Defenses by late heroic or early Paragon.
Most players, even those with semi-decent numbers in all 3 NADs should eventually take at least one and sometimes two or more defense feats (in the example above, Improved Defenses or Superior Reflexes plus Epic Reflexes).
If the PC in this example takes both Superior Reflexes and Epic Reflexes, the PC would have a Reflex Defense of +30. That's a solid get hit on an 8 at level 30 by same level foes, but it cost 2 feats. The PC might also pick up an item with a +1 Reflex bonus as well.
The non-lowest NADs don't have this issue and the player doesn't really have to worry too much about them. Yes, the 1st level monster hits Will defense 15 with an 11 and the 30th level monster hits Will defense on an 8, but this isn't game breaking. With the sheer number of defensive abilities and items that a player has at level 30, getting hit on an 8 isn't crushing and a single feat, Improved Defenses, will get it back up to 11.
But getting hit every time on a 2 is crushing.
My suggestion. Get your DM to give a feat bonus of +1 to hit and NAD defenses per tier and forget about most of the problem.