Is pulling back on a bow, aiming and firing a "cast?" Many pen and paper games allow quick casts, free casts, etc. and I don't really feel there should be a minium casting time on what counts as a spell. Even look at the barspells in 11 with full Fast Cast gear, that's hardly a casting time if you have gear to back it.
This wasn't very fleshed out I admit. But I also don't think being in melee range discounts them from being a caster, I was just trying to address it.
I see your point here but a few things: 1)Even the tanks don't share gear all of the time. They seem to be getting better about this, but you can't wear esoteric PLD gear on WAR for instance so they break that cycle themselves on occassion. I don't think keeping the gear like that is so much intentional to keep people playing tanks as it is keeping it to 1 model instead of 3, but that might just be me seeing the glass half empty. 2)A little horizontal progression would allow people to gear more than one set of jobs a patch cycle and allow people not only to gear that tank and that dps, it might spur people to level tanks knowing they'd have a chance to gear it to be relevant that patch cycle. One of the main draws to this and FFXI was the ability to level everything on one character, and I feel it's sorely underutilized here with the lockouts. Many people don't play tanks because they don't like the playstyle, mechanics, etc of the current jobs and having one out of left field might do wonders for the tank population.
As for contesting gear I don't really think that's much of an issue. Not only do you have ways to avoid quequing with people that might take your gear DPS can and do contest gear with every DPS. Full BRD/MCH parties happen, maybe you think it's a big deal because you are now the tank and are used to fighting one person for drops at best but we've been doing fine fighting up to 3 others. Should I just drop parties with multiples of my job/role? Will you gear up a bit slower than a traditional tank? Maybe, but if you had more varied content and more horizontal progression you can do solo content every so often for decent gear, tome gear, 4 man parties and still get there. And this could go the other way as well, releasing DPS/healer jobs that use the tank gear would stop just the up to two tanks from having free reign on gear.
It absolutely does take time, but they have to try. Tome #567345384 capped at 450/week across all jobs and two dungeons doesn't really do much to address things. And I'm not saying they should do this for patch 3.5 or whatever, but expansions are the place to fix the big stuff and they could attempt it there. However I do kinda feel like this is a bit off topic, unless you feel RDM is a full caster.