I'm not sure where the idea of 3 tiers of gear came from, but instead of bloating the game with so much junk, why not give us good gear with different stats?
For example, one of the new amulets comes with a ton of health and block. So give us another option with less health and tons of critical and more damage. This way we can gather different sets of gear for different purposes, and not just have one set of 'best' gear with tons of 'junk' gear.
Another example: as far as I know, we still don't have a good weapon that gives high block, low crit with good pierce.
I agree with your sentiments. From Aquila onwards there is a trend of one set thats great and the rest pointless. With waterworks we had just one set and everyone was fine with that. Including more sets means more time spent in one place trying to get items, which is fine when each set has some meaning and usefulness. I collected all 5 sets from Tartarus for most of my wizards not because I wanted all 5 but trying to farm the gear I wanted I ended up with them all xd. The same goes for Darkmoor I must of completed all the sets while trying to get my last piece of tier 1. If the gear sets added variety in style as you suggested it would make more sense to collect them all if you so wanted to then you could switch around as you preferred and further tailor your wizard to your playstyle. Having one good set one mediocre set and one pointless set only adds to the frustration of farming. I doubt they will change the format now, but hopefully they will take some note of this.