The problem I tended to see in my games that made me make a change was the old "I'm not trained in that skill, so I shouldn't even try it" issue.
Thankfully I tend to find that's not an issue in my group. That's not to say that players don't look for approaches that can draw support from their bigger numbers, but if they really
want a certain outcome, and the only way to get that is to do a thing their PC is not too good at, then they will have their PC try that thing. (This comes up most often in relation to the low-CHA fighter with no trained social skills trying to persuade people. But occasionally it is the low-STR melee-weak invoker/wizard trying to take an opportunity attack or even a regular melee attack against someone/thing he really doesn't like.)
What I find helps with this (which I'm not meaning to imply you haven't tried at your table - I'm just setting out my own approach) is a "fail forward" style resolution of the Burning Wheel or DitV sort: if the check fails, then the PC (and player) don't get what they wanted, but I narrate an outcome in which stuff keeps happening (ie it's not just "Sorry, didn't work). So the anti-social fighter trying and failing to persuade a NPC (ie player fails a low-bonus Diplomacy check) might lead thinks down a less happy path for the party, but it doesn't stall the action at the table.
I don't like ABIs, characters being able to have every skill in the book, lots of 'tax' mandatory choices, nor ways to combine or acquire vast swaths of the book. I like systems that say definitely "yup, this guy is a dwarf veteran axe man who has a skillset acquired in the orc wars, and a set of propensities to go with it." Its fine if he also has a strange fascination with elvish lute music and he's actually a very sensitive and insightful guy underneath the gruff exterior. Its just not OK if that's all not mechanically supported because he's got half the skill list and had to take 5 thematically inappropriate feats in order to have an acceptable DPR.
I don't want a longer list [MENTION=72450]HUMAN[/MENTION] Target. I want a SHORT list because of my view of skills as 'knacks'. I mean, you can probably make some arguments for more of these, but its a slippery slope and you eventually get down into the weeds where its hard to decide which one really makes narrative sense in a given situation. If I were to go on a spree of overhauling the list, I'd actually cut it back to something like the approaches that are used in Fate Accelerated. So maybe 6, and let each PC have ONE, or possible 2 if they really want.
I've got no problem with that. In the 4e context, I'd be pretty happy if Athletics and Acrobatics were folded together, with an option to test on STR or DEX depending on the logic of the fictional situation.
My point about thieves/rogues wanting six skills was more framed in the context of the game as it is currently presented.
most PCs are actually pretty good at probably half the skill list. I mean, with a standard array and 2 race bonuses you are likely to have 3 attributes with +2 or higher bonuses. Many characters have a skill bonus in one or two things, and a goodly number have a whole bonus trained skill. Heck, you can have JoT for the cost of one feat slot, not a horrible price. Even a level 1 PC can be a pretty decent 'McGyvver' type (actually it gets harder at high levels unless you start really investing).
I was going to make the point about higher levels and then saw that you already made it.
Here's the PC summary chart from my 30th level 4e game:
[sblock][TABLE=”width: 100%]]
[TR]
[TD][/TD]
[TD]
Derrik[/TD]
[TD]
Jett[/TD]
[TD]
Malstaph[/TD]
[TD]
Ravian[/TD]
[TD]
Tillen[/TD]
[/TR]
[TR]
[TD]AC[/TD]
[TD]45[/TD]
[TD]46[/TD]
[TD]43[/TD]
[TD]47[/TD]
[TD]47[/TD]
[/TR]
[TR]
[TD]Fort[/TD]
[TD]41[/TD]
[TD]42[/TD]
[TD]33[/TD]
[TD]39[/TD]
[TD]42[/TD]
[/TR]
[TR]
[TD]Ref[/TD]
[TD]39[/TD]
[TD]43[/TD]
[TD]39[/TD]
[TD]45[/TD]
[TD]36[/TD]
[/TR]
[TR]
[TD]Will[/TD]
[TD]40[/TD]
[TD]48[/TD]
[TD]45[/TD]
[TD]44[/TD]
[TD]45[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]hp[/TD]
[TD]224[/TD]
[TD]171[/TD]
[TD]139[/TD]
[TD]173[/TD]
[TD]222[/TD]
[/TR]
[TR]
[TD]Initiative[/TD]
[TD]+21[/TD]
[TD]+28[/TD]
[TD]+21[/TD]
[TD]+24[/TD]
[TD]+19[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Passive Insight[/TD]
[TD]29[/TD]
[TD]27 (29)[/TD]
[TD]44[/TD]
[TD]33[/TD]
[TD]37[/TD]
[/TR]
[TR]
[TD]Passive Perception[/TD]
[TD]29 (32)[/TD]
[TD]27[/TD]
[TD]39[/TD]
[TD]42[/TD]
[TD]30[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]STR[/TD]
[TD]26 (+23)[/TD]
[TD]10 (+15)[/TD]
[TD]12 (+16)[/TD]
[TD]12 (+16)[/TD]
[TD]14 (+17)[/TD]
[/TR]
[TR]
[TD]CON[/TD]
[TD]20 (+20)[/TD]
[TD]14 (+17)[/TD]
[TD]13 (+16)[/TD]
[TD]16 (+18)[/TD]
[TD]18 (+19)[/TD]
[/TR]
[TR]
[TD]DEX[/TD]
[TD]18 (+19)[/TD]
[TD]26 (+23)[/TD]
[TD]10 (+15)[/TD]
[TD]28 (+24)[/TD]
[TD]14 (+17)[/TD]
[/TR]
[TR]
[TD]INT[/TD]
[TD]10 (+15)[/TD]
[TD]12 (+16)[/TD]
[TD]24 (+22)[/TD]
[TD]10 (+15)[/TD]
[TD]12 (+16)[/TD]
[/TR]
[TR]
[TD]WIS[/TD]
[TD]19 (+19)[/TD]
[TD]14 (+17)[/TD]
[TD]28 (+24)[/TD]
[TD]26 (+23)[/TD]
[TD]20 (+20)[/TD]
[/TR]
[TR]
[TD]CHA[/TD]
[TD]12 (+16)[/TD]
[TD]28 (+24)[/TD]
[TD]12 (+16)[/TD]
[TD]15 (+17)[/TD]
[TD]28 (+24)[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Athletics[/TD]
[TD]+28[/TD]
[TD]+15[/TD]
[TD]+15[/TD]
[TD]+20[/TD]
[TD]+18[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Endurance[/TD]
[TD]+35[/TD]
[TD]+17[/TD]
[TD]+15[/TD]
[TD]+19[/TD]
[TD]+17[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Acrobatics[/TD]
[TD]+19[/TD]
[TD]+28[/TD]
[TD]+14[/TD]
[TD]+33[/TD]
[TD]+13[/TD]
[/TR]
[TR]
[TD]Stealth[/TD]
[TD]+19[/TD]
[TD]+30[/TD]
[TD]+14[/TD]
[TD]+23[/TD]
[TD]+15[/TD]
[/TR]
[TR]
[TD]Thievery[/TD]
[TD]+19[/TD]
[TD]+23[/TD]
[TD]+14[/TD]
[TD]+23[/TD]
[TD]+13[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Arcana[/TD]
[TD]+15[/TD]
[TD]+21[/TD]
[TD]+43 (45)[/TD]
[TD]+15[/TD]
[TD]+16[/TD]
[/TR]
[TR]
[TD]History[/TD]
[TD]+15[/TD]
[TD]+16[/TD]
[TD]+43[/TD]
[TD]+15[/TD]
[TD]+16[/TD]
[/TR]
[TR]
[TD]Religion[/TD]
[TD]+20[/TD]
[TD]+16[/TD]
[TD]+41 (43)[/TD]
[TD]+20[/TD]
[TD]+21[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Dungeoneering[/TD]
[TD]+21[/TD]
[TD]+17[/TD]
[TD]+35[/TD]
[TD]+23[/TD]
[TD]+20[/TD]
[/TR]
[TR]
[TD]Heal[/TD]
[TD]+24[/TD]
[TD]+17[/TD]
[TD]+24 (26)[/TD]
[TD]+23[/TD]
[TD]+20[/TD]
[/TR]
[TR]
[TD]Insight[/TD]
[TD]+19[/TD]
[TD]+17 (19)[/TD]
[TD]+34[/TD]
[TD]+23[/TD]
[TD]+27[/TD]
[/TR]
[TR]
[TD]Nature[/TD]
[TD]+19[/TD]
[TD]+17[/TD]
[TD]+35 (37)[/TD]
[TD]+30[/TD]
[TD]+20[/TD]
[/TR]
[TR]
[TD]Perception[/TD]
[TD]+19 (22)[/TD]
[TD]+17[/TD]
[TD]+29[/TD]
[TD]+32[/TD]
[TD]+20[/TD]
[/TR]
[TR]
[TD][/TD]
[/TR]
[TR]
[TD]Bluff[/TD]
[TD]+16[/TD]
[TD]+29 (33)[/TD]
[TD]+18[/TD]
[TD]+17[/TD]
[TD]+26[/TD]
[/TR]
[TR]
[TD]Diplomacy[/TD]
[TD]+16[/TD]
[TD]+35 (37)[/TD]
[TD]+29 (33)[/TD]
[TD]+22[/TD]
[TD]+35[/TD]
[/TR]
[TR]
[TD]Intimidate[/TD]
[TD]+16[/TD]
[TD]+37 (41)[/TD]
[TD]+20[/TD]
[TD]+17[/TD]
[TD]+37[/TD]
[/TR]
[TR]
[TD]Streetwise[/TD]
[TD]+16[/TD]
[TD]+24 (26)[/TD]
[TD]+16[/TD]
[TD]+17[/TD]
[TD]+24[/TD]
[/TR]
[/TABLE][/sblock]
The AC gap is 4. The NAD gaps are 8 or 9. The skill gaps go into the 20s and even 30 for Arcana.
I know your system eliminates ability score increases, which is some of that gap. But it also results from the fact that (in core 4e, at least) item or inherent bonuses to AC and other defences are ubiquitous, whereas skill bonuses are much more varied. Feats are similar in this respect.