Ahh the days of spellbars full of all ranks of moonfire, and short cast frostbolts with a lot less damage, but the same slow.
Yeah, balancing really went to shit when they got rid of ranks. They must be using formulas or something, so the scaling is the same for everything, and they can't think "Ohh, class X is OP in bracket Y. Lets nerf spell Z a bit at that rank." No, instead they buff something that's weak at endgame, and the formula makes it OP across half the lower levels, where it's counter class/spell doesn't exist.
You say a certain minimum of spells? But how do you see what the minimum is? 10? 20? 30? I'ld say they would still have to give something for getting better and actually progressing, even it it were just cosmetic items.
I'd have to say about the same number we had in 19s back in TBC. Enough to fill 1-0 and a few keys around WASD, without using modifiers or macros (so you can have everything on about half a dozen keys with modifiers and macros). Add more and you end up making some abilities redundant compared to new ones, or having too much duplication of capability between classes. At endgame the number of abilities you have is just stupid. You regularly use only very few of them, and a lot of them only in very specific circumstances.
A good equivalent to rock-paper-scissors(-lizard-spock) between the classes, with every class having it's hard counter, combined with limiting numbers of any one class in a BG, could see much more strategy in BGs.
Or they could take another lesson from Firefall/FPS games. Let people change class during the game (something you can do with no levels/gear, and a hard PvE/PvP split). In Firefall there are battleframe stations in the spawning areas, so after you die, you can switch to another class. That way a team stacking one class gets countered by people respawning as it's counter.
Firefall and GW2 are also strictly against pay to win, instead having a lot of items that are either cosmetic or convenience only, like paint jobs, hats and headgear, pets, mounts, or temporary XP and resource gathering boosts. WoW
is pay to win, not just because of F2P-vs-P2P, but because the longer you've subscribed, the more heirlooms and enchants you can throw at lower level PvP characters.
More custom gear, mounts and pets could be rewarded for gaining PvP ranks, and it doesn't need to have any stats on it, or give any advantage. It should be "I get to wear this because I kick ass", not "I get to kick ass because I wear this".
Right now every expansion sees a crap-ton of PvE gear, new mounts, pets and vanity items from PvE, but PvP only gets a single set of gear for each class, and mounts for being above a certain rating. PvP rewards just plain suck, and they aren't helped by having good PvPers walking around in PvE gear, instead of something that stands out as different from PvE gear, as well as what most PvPers wear.
No stats would mean full sets, and outfits that look good (provided Blizz can make some decent armor sets). Letting players customise the colors would help.