Yes, if you want to jump into a mid+ tier guild, no, you are not going to do it as a warrior, and to lesser extent, pally/sk. You could jump in if you were a dps/healer, but not as a tank. But those people aren't going to be doing much to help the guild. Yes, as a tank, you are dependent on your gear to make you able to do your job. Did you not understand that warriors were gear dependent when you creating your warrior?
If you want to raid, it requires *WORK*. Including farming tmaps, and lower tiers REPEATEDLY. AAing everyone in the guild to a decent point. At 100ish AAs, your lacking some of your major AAs, much less many other good/decent AAs. Bitching because higher guilds wont take you into raids/guild? Seriously. GET OVER YOURSELF. If you want into the raid game, go start yourself a guild, or find a low tier guild that is looking for a warrior. ALL classes have to raid up from low tier on up before they are worthwhile in high tier environments, not just warriors.
If you want an example of a recent warrior who isn't a reused bot, look at Tyvec.
As a tank, raids count on that toon to have the best gear possible. Because if the tank(s) are weak, the raid goes splat. PERIOD. If your guild is tier 8, know how long it will take to regear/AA/tome/Charm a new tank before they can continue raiding in a similar tier? Think 6 months or so. A guild isn't going to wait for 1 person to gear up before the rest of the guild can continue advancing.
This isn't a flaw or a problem or any other such bs. It is merely the point of a roleplaying game. Its like saying that your a lvl 40 warrior, lvl 65 chars wont let you be main tank for their group, and your saying you have a problem with this. So you think your lvl 40 warrior should be able to do something to allow warriors to act like a monk. Do you think a 65 group would want a lvl 40 monk? You HAVE to advance more before your useful in the higher groups/raids.
Levels are what you measure how hard of zones you can take on from 1-64. At 65, your gear/AAs is what you use as a measure. Think of a 65 warrior in DM/100AAs as a level 30 toon. Mid-tiered guilds are using the equivelent of a lvl 45 warrior. A tier-10 guild is using the equivelent of a lvl 65 warrior.
Now, about warriors fulfilling only 1 role?
Well, what about clerics, they only fulfill 1 role as well. And it wasn't fair, because all the guilds are only recruiting DPS. They want an ability to temporarily change all their healing spells into wizard spells. What do you think that would do for the game?
Or how about a monk. And they didn't like their role. And it wasn't fair, because all the guilds are only recruiting tanks. Sure, they can tank ok, but not great. They want the ability to magically turn into a warrior, and give up their dps. What do you think that would do to the game?
If you start along the path of magical switching to other classes, eventually there will only be 1 class, and everyone can do exactly the same thing as any other person.
So stop whining. If you want to do X job and you are a Y class, either give up your toon and start a new X. Or learn to enjoy doing the Y job.