I could do with some convincing about that...
The higher the skill is, the longer it takes to increase. But, the higher a skill is, the more it contributes to leveling up when you increase it.
A specialised character will have high skills that, when increased, contribute more to leveling up; but those skills will take longer to increase. A jack of all trades will have low skills that are faster to increase; but more of them are needed to level up. It's not clear to me that the rate of leveling up will be slower for the second type of character, because those two aspects which go into leveling up might balance each other out.
My impression of higher skills -> count more to leveling up was that it's designed to promote specialisation; and it's also not clear to me that a side-effect of the system is that specialised characters will level up faster. It's just that specialised characters will be stronger than generalist-type characters, where both have leveled up the same number of times.
This is also my take on it, raising skills gain you a score, call it experience points, or level points. You get more points for raising high skills than low; the level point requirements for levelling up will increase for each level as experience points do.
It’s probably still harder to raise high skills than low but I guess the level point score makes them more effective as in levelling up.
Say going from level 3 to 4 require 50 uses of skill and gives you 3 the level point, going from 30 to 31 require 250 uses but gives 30 the level point.
Not a bad system if balanced, however it has one major problem with non combat skills,
If you do a lot of alchemy and armor crafting at low level to get money, add some lock picking and pickpocket and some social skills. You will suddenly be at high level while being a novice fighter, just as if you had alchemy and lockpicking as majors in Morrowind/ oblivion and used them a lot.
The same is true for some other skills in Oblivion but in lesser degree.
Only solution I see is to let the non combat skills give you less level points, not perfect but this is probably the bomb in Skyrim gameplay.