I have noticed how quickly some people have become incensed after reading the changes to the gear system. I had hoped to present an account of what can and cannot be inferred from this system. I doubt my analysis is without flaw, and if anyone has a legitimate, constructive response or refutation of any of what I've said, I would genuinely love to discuss it! In any case, read on!
After several careful readings of the Blizzard post on the gear system in WoD, we can (so far) conclude that it is not a copy of the Diablo 3 system. It is not implying that all of the secondary stats are randomized at the point of looting. It is saying the bonuses are random. So, an item might drop that has haste and mastery as it's default secondary stats. We have no reason to believe this will not always be on the item, every time, ever. The difference is, one time the item might have a gem slot (we don't know how powerful this is, as we don't yet know the new gem system) and sometimes a possible random tertiary stat, like cleave or movement speed. From what we've seen, the tertiary stats look a little more like flavour, such that they are not huge or game changing bonuses. The same could be said for the gem slots. Yet, in world first progression raiding, they could make a slight difference that could be powerful at that level. It also happens to be that players raiding at that level will often min-max and enjoy raiding for the perfect gear. Don't freak out yet! We need ilvl, gem stats, and tertiary stat values before we assume a broken system.
So far, what we know is: Armor will be dynamic (switches primary stat between specs), non-armor will be static (remains the same between specs), and some gear could potentially have a gem slot(s) and / or tertiary stats. This is NOT a complete randomization of all the stats on each item on a drop per drop basis (so far as we currently know). Think logically, if that were the case, it would mean that they would only really need one item for each armor type and equipment slot in order to provide suitable gear for players. That is, there would only need be one plate boots (which have random stats for each drop), only one leather chest (random stats for each drop) etc. Any more would be redundant. They made no implication that this would be the case.
All the best!