mainly because if you look at rawr, they tend to overweight crit over haste a huge amount. And while there might be slight min/max differences, I tend to look at the overall scheme.
In other words, I'm not just looking at 1 piece of gear, I'm looking at overall upgrades. I run at 507 haste, 17.45% unbuffed in human form crit. So while I might be able to gain a slight amount hear than there, am I doing it at the expense of something else.
All I can really say is that I went by crit early (about 22% unbuffed and about 250 haste), and was around 3.5k dps on patch, but with switching out gear for pure haste, it went up extremely fast, to now at 5k. Thus I must be doing something right.
EDIT: so I'll err on the side of 5k dps.