I'd be fine with the one-item-per-boss system if what was dropping was actually well itemised, legitimate individual upgrades compared to black hole/campaign level gear.
Problem is, they're not, and depending on your class the extent to which they've botched your items can be pretty dramatic. I've only a vague idea how it is for most other classes, but requiring me to collect two-three entire sets worth of items just to correct the horrendously poor itemisation on the commando Dread Guard gear, whilst dropping one token/other item at a time? Screw. That.
Stil, even fixing the itemization, only 1 single drop is extremely low, i can live with 2, 1 DG set item and 1 Hazmat drop but only 1, no way.