Expertise wasn't a "fix" it was a way for flavor choices to be viable, for instance, a Dwarf Fighter with a 16 Strength and +2 Weapon can still be perfectly viable without "buying" an 18 Strength or a character to flavor for extra accuracy vs. raw damage.
Ok, here's my question:
Did you feel that a Dwarf Fighter with a 16 Str and +2 proficiency weapon was 'behind' the Fighter with 18 Str and a +3 proficiency weapon?
If so, why do you think the Dwarf Fighter with 16 Str, a +2 proficiency weapon, and Expertise... isn't still behind the Fighter with 18 Str, a +3 proficiency weapon, and Expertise?
Worse than that, how do you feel about the Dwarf with 16 Str, a +2 weapon, and
no Expertise compared to the Fighter with 20 Str, a +3 weapon, and Expertise? Suddenly, the dwarf is swinging at -4 compared to the other guy.
That's my real issue with this - it adds yet another way for an optimized character to be ahead of a non-optimized character. Previously, by Level 30, a non-optimized character might be at -3 or -4 compared to an optimized character. Expertise basically
doubles that difference.
And yeah, extreme cases might widen the differences ever further, but I'm just looking at regular stuff - one guy has higher starting stats, a longsword instead of a warhammer, and takes an epic destiny that boosts his Strength. Those few extra points of accuracy certainly exist, but aren't the end of the world. But add in Expertise, and the difference becomes really noticeable.
At level 30 - honestly, by level
11 - not taking Expertise is taking a huge hit to power. And no feat should be that necessary. Sure, you can play without it, but when it is worlds better than all your other options, something is clearly wrong.