Or he might get his DS just in time before they die while you have a few extra seconds which you spend on weak HP builders and the adds die just before YOU get your next DS in. Now you both have the same amount of strong attacks except his are hiting for a lot more with all that extra mastery and criting more often.
Both scenarios are equally likely and that's why we have stat weights for average situations. Those lucky/unlucky situations even out over a longer fight unless the adds die extremly fast every time in which case mastery/crit would actually be better.
I might have misunderstood you here, are you saying that crit is worse than what its sim value is because you might get unlucky and not crit more with higher crit rating?
What sort of argument is that? That's like saying that t15 4set bonus was useless because you might get unlucky and not have it proc at all.
Frost DKs with 2hander are stacking crit. They have no extra mechanic depending on crit, on the contrary they actually have a Killing Machine proc that devalues crit rating because it gives them a guaranteed crit on their next Obliterate or Frost Strike.
Why do they do it? Because it gives the highest damage on average. Haste, mastery and half a strength are simply even weaker.
You should go for stats which perform better on average and not think too much about arbitrary situations where you might get extremly lucky/unlucky unless there are some VERY specific situations on some encounters.
I don't think that item level squish would solve the problems you are talking about, but I do expect and hope for some tweaks in the combat ratings system for next expansion as well.
Just as an interesting sidenote, the stat weights for haste, mastery and crit differ by less then 0.1 for me personally.
Now napkin math says that I would need to gem/reforge about 30k of rating incorrectly to lower my dps by 1 %. As my haste/mastery would go down and crit up, the difference between the values would increase so in reality a little bit less rating would be needed, but you get the point.
Things such as killing a boss a bit faster (as your raid gets better geared and knows the fight better) which will give you higher uptime on pots/lust, higher or lower uptime on CDs depending on the exact length, slight changes in your tactics or simply RNG will have much higher impact on your DPS on a single attempt than reforging. You would need to test different gear setups many times in the same situation to find out which is better.
Therefore saying that some good player X from guild Y reforged this or that way and ranked well on WoL doesn't really mean that much.