I grant that the new three rows are probably sufficient to include each of almost any character's skills once, However the multi-levelsystem lends itself to grouping skills by things like what kind of situation they are suited to, long countdowns vs. short countdowns, mana-based skills vs timed skills, etc. and this has the problem that some skills may need to appear more than once, which may push the limits of the currently available space. About two more rows would probably be enough to alleviate this.
It's a bit too late, but I want to say that I like this suggestion. It does appear to be a bit redundant since (as Bohandas himself pointed out) three words give plenty of space, but the more pedantic players will appreciate it (because it truly is nice to be able to group spells according to their desired use).
Actually, now that I think of it, some really ability heavy builds (like many pure mage builds) may actually exceed even the space in the three level skill belt. I'm playing a character now with only 4 empty slots left with six dungeon levels still to go.
