The Rakata set, for example, has 255 on it. It's on every piece. Now this is just speculation, I don't have any math to support this, but I'd wager it's our least beneficial stat (between power, crit, and surge[maybe not surge after the nerf]).
Haste's purpose in the long run is to pump out more heals over shorter intervals. It's exceptional, and without a doubt the best stat for a healer, when resource management is easy or a non-issue. But as an operative, with energy as our resource and the way it regens, spam casts are certainly not a viable option. Baseline, Kolto Injection takes a quarter of our energy, and talented it's already a fairly short cast. So not only is spamming out of the question, it doesn't receive a great deal of benefit to begin with.
The only ability that alacrity really shines for is Diagnostic Scan. Mine is down to about a 2.5 sec channel, which is honestly quite nice in an energy intensive situation. But it's nothing worth stacking alacrity over.
The way I see it is this:
We've got 6 healing abilities (7 if you count a talented toxin scan), 3 of which are casts. 2 of said casts we use often (K. Injection, D. Scan), one rarely if at all (K. Infusion). The rest are HoTs and an instant. As said before, D. Scan is the only one of 6/7 abilities that receives a true benefit. Hasted K. Injection's only benefit is for a clutch heal after a spike, and even then a power boosted, or crit heal would be more useful.
So if only one of our abilities, arguably our weakest heal at that, is receiving real benefit from it, why is there so much on our gear? Honestly, if you want to make Alacrity useful for Operatives, tweak it so that it also increases the rate at which our HoTs tick.