Good post and well thought out, and overall I wouldn't object if it were done that way. That said, I personally think a reduction in cooldown would be better. As specialists have fewer spells to choose from, it seems reasonable that they should get to use them more often. Otherwise, once you've cast all the spells that make sense, it can be a long wait before you can actually do anything useful.
Sure, having skill specialization lower cooldowns with more points is another good approach. I'm a bit less keen on it though, because cooldowns have a larger range: some skills have a 1 turn cooldown, others have cooldowns as long as 20 turns. I assume Larian will want some skills to have a minimum cooldown to avoid spamming and for balance, which means some skills won't be affected, and on long cooldown skills, even a 4 turn shorter cooldown won't matter.
If however this should prove too complicated.
A simpler way to re establish flexibility would be to remove the limit on skills / spells by level and reinstate the limit on skills / spells by ability rank.
I must be missing something, because that sounds almost exactly like the system before the second-most-recent patch, except that in the current system, ability rank bonuses were transferred to Talents.
