Baldur's Gate game had a good number of skills with 5 proficiency levels per skill max (with class restrictions for each class) and only 1 skill per... I forgot, was it 2-3 levels?
If it works well in how the game plays, then all's fine. The game will most likely open up to tuning as time passes anyway, as people will make tools for tweaking what Larian won't let you tweak yourself. And they seem to be offering very liberal tweaking, if I'm not mistaken.
I could be mistaken, seeing I just caught a cold, I'm in woeful pain and may have lost touch with the world as it is :s
