AbdulAlhazred
Legend
While I'm not a huge fan of 13th Age (I certainly don't dislike it, but there are any number of Story Now Heroic Fantasy systems I'd rather be running), I don't really see the similarities to 3.x outside of (a) the basic d20 chassis and (b) the fact that Tweet was involved in 3.x as well as being the co-creator (with 4e's Heinsoo). Obviously I agree with you regarding the lack of symmetry in class resource scheduling for and lack of keyword dependency (including Power Source).
But for my money, the experience of 3.x was all about:
a) Terrible Action Economy - Heavily favoring casters while very negatively impacting mobility (perpetuating battlefield stagnation) and melee characters (PCs and NPCs aliike)
b) LFQW...cubed
c) Horrendous combat budgeting (in many ways directly related to a and b)
d) Granular noncombat task resolution predicated on process-sim and featuring fiddly build mechanics and binary (non-dynamic) action resolution
e) Magic Item Economy and all the notorious impact that proliferated onto the rest of the system and setting as a result
f) An exceedingly narrow sweet spot of play
g) Related to (b), but needing a spot on its own, is the overwhelming, conflict-neutering power of Divinations, Conjurations, and Transmutations.
13th Age doesn't feature any of those and pushes in the opposite direction toward 4e (along with being heavily focused on fail forward and the story components of PCs - a la 4e)
Yes, I just think that it did so from a starting point that was more 3.0 than 4e. I mean, its like a do-over, what if we took 3.0 and made a more story-centric and narratively driven system from it, but without much reference to what 4e did. You could look at 13a's 'recoveries' as being somewhat akin to 4e's Healing Surges/Second Wind, but not VERY much like it, and weirdly more reminiscent in effect to 3.x with a modest number of healing items in play.
But TO ME the real heart of 4e's mechanical appeal IS the healing system, the action economy, and the regularized power-centric class designs, none of which is particularly evident in 13a. So they have some things in common in terms of goals, and start from a common design philosophy, but IMHO go in quite different directions with it.