Coming from a guild that gives 65% of its warrior/rogue drops to rogues, I can tell you it sucks. Not only for 4h (which I don't see my guild doing any time soon because of this reason) but for anything in naxx, geared tanks will make your life a hell of a lot easier. I can't even count the number of times we wiped on thaddius phase1 due to tanks getting gibbed, or even the MT dying in phase 2 just because hes in 7/8 wrath and 1 piece of might.

Give the pieces to warriors.

Gear helps tanks, but no matter what gear they are wearing, they will still die with sloppy heals.

So dont think T3 loot will just magically make an encounter easy. It just adds a little buffer for error.

Rule # 1: Its always the healer's fault.

It won't magically make the encounter easy, but it does drastically reduce the amount of damage your MT takes. Isn't that why a lot of guilds gear up their MT first?

4k+ crits are not fun

I think you're missing my point -- I don't think you should prevent any rogues from bidding entirely, everyone needs gear, dps is important too. However, if you look at BWL, rogues get bloodfang, and tanks get wrath. Then AQ40 rolls around, rogues get deathdealers, and tanks get nothing. The conquerers chest is a pretty clear upgrade for most, and some people prefer the helm, but for the most part people are still wearing a lot of wrath. The rogues have other pieces other than bonescythe where they can upgrade their gear, there's even some gear in AQ40 thats straight up better than bonescythe. It would be more beneficial to the guild, coming from a progression standpoint, to let your warriors pick up the gear, espcially if you plan on killing 4h. Now I have no personal experience with 4h, but AFAIK its not realistically doable without at least 6 warriors in 4/9 dreadnaught, preferably 8. So until you get that squared away, you're going to be stuck. It's the fact that its necessary for the warriors, and not necessary for the rogues.

4H is "doable" with zero tanks in 4/9 Dreadnaught. But the more tanks in Dreadnaught you have, the less bad luck you're succeptable to. Even on farm, 3 taunt resists in a row (or 4 or 5!!) is tough to deal with. It may be doable sometimes (CS/Mocking Blow being up + the taunt after not getting a resist), but it really throws a wrench into the cogs.

In most good guilds on most mature servers, most of the rogues already had most of their deathdealer before Naxx was ever released. I can see your points now that the four horsemen are 2 bosses away for us, but not having given the rogues tier 3 prior to this point would have seriously hindered our guild's progress. Tank death has never been a problem assuming our healers were using the correct healing strat for the encounter, and gearing up only the MT a lot and one OT a little worked well for us. Maybe our mages are just underperforming, but the weight of DPS has fallen heavily on the rogues' shoulders, and we just wouldn't have been able to take up that slack without the major gear upgrades that tier 3 affords.