once apon a time, there were 7 aspects.
hawk, for a static non scaling ranged attack power buff , monkey, for dodging when enemies were close, cheetah and pack, which we still have, aspect of the beast, for anti tracking and bonus melee attack power, and wild, for a static nature resist buff, and viper, for mana regeneration on attack hit at the price of 50% reduced dmg (also had viper sting which siphoned mana from target to refill our mana pool)
In wrath, they combined monkey and hawk into aspect of the dragon hawk, static boost to dodge and ranged attack power.
In Cata, dragon hawk became hawk, lost monkeys effect entirely, along with aspect of the beast. we lost viper and viper sting, along with scorpio sting, got aspect of the fox and the focus system. Fox gave us focus on melee hit and made our focus generating shots cast able while moving.
In mists, wild went away, along with all resistance buffs and stats on gear (was gone pretty much anyway as of wrath), and hawk became a scaling buff. we also got the anti tracking beast back, and lost melee weapons and any reason for the melee attack power buff.
In 5.1 we lost aspect of the fox and its effects were made baseline. The trending theme with blizzard is that aspects should be made simple and easy. They don't want to take away our ranged attack power buff, or our aspect of the cheetah/pack speed boosts. could they ad more interesting aspects? sure, but in order for them to get any real use (which lack of use is what got so many removed, or unintended use for those who remember the days of the melee hunter) they would have to make aspect of the hawk baseline, and probably turn our aspects into cool downs like they did with shaman totems. some would prob not have a cd (like cheetah/pack, unless they removed the daze and make it a stronger speed boost) but then our aspects would be interesting.