The benefits of stacking stamina are very well defined at this point, but I agree on the point that the focus is a little too heavy on the stat. Yes, it is necessary to stack stam to survive the ludicrous amounts of burst damage every boss puts out. Combined with the fact healers never run out of mana these days despite the fact they never stop casting and threat outputs were made easy...... there's no other options or leeway. There's only the option to stack stamina.
Now this isn't to say Blizz should do away with tanks stacking stamina altogether, but it'd be nice to have something else to focus on for once. Cataclysm aims to solve at least one problem, by not making bosses hit too hard. The new healing model requires several heals to get a tank up to top health (from low health), 4-5 hits to kill a tank compared to the 2-3 these days, and 4-5 casts to today's one cast. There's probably still some fine tuning in there needed, but you get the idea.
Because dying won't happen quite so quick in Cata, there probably should be some wiggle room. You can have the option to throw in some more avoidance (make you easier to healer overall, if a bit random), some more threat (hit & expertise mostly, and this also doubles as more DPS as a tank), or maybe just a bit more stamina because you feel like it. While understandably we don't want to do calculus to figure out which stat is best for us, I'd really rather not have just one stat to rule them all.
Maybe it's just me, but stacking only one stat isn't my idea of a fun game mechanic.
He who isn't afraid to stand by his ideals...
Isn't afraid to stand alone.