TES games always gave us lot of freedom in character creation in terms "play as you want"
Class system were "necessary evil" 11 years ago, since most mmo's had this class-system at that time.
But now wee see that multi-classing possible and works rather fine (well, some combos better than others, but, so was with 'solid' classes, some were better than other in specific roles/content)
So, maybe its about time to just set "class" as a preset in the beginning (like onebar setup when we create new char) and let to change everything freely(like drop all your skill lines and replace with others)?
At this moment everything lest from "class" system - some leader-boards (which lost most of meaning anyway, does it really matter who was 'base' class if you use all skill lines from 3 different 'classes'?) and "class sets", but, they already bound more to specific class-trees, rather to class itself, so there are little reason not to adjust them from being "class"sets to be "skill line"sets.