Since you seem to think I'm talking out my butt or something... I have been progression raiding for the last 4 years. I've been an officer and guildmaster. I'm currently a raid leader. I've achieved as high as World #7 ranking as a healer in WoW. I've done progression raiding in this game as a Sniper, Marauder and Sorc healer. When our Sin tank goes on vacation this month, I'll most likely be filling his spot on mine. I do know what I'm talking about.
"Bring the player not the class" is true only to a certain extent. Fight mechanics preclude any group from stacking melee. Sure you can have more than 2, but you're making things unnecessarily difficult for your group if you do. This game is not melee friendly; that's not really up for debate. Any serious progression group is going to bring a Marauder. Along with being one of the top parsing classes, Bloodthirst is too good not to have on burn phases (last 10% of TFB, Kephiss, Toth and Zorn, etc.) This is the most blatant example of "bring the class". We went as far as having someone level up a Marauder 2 weeks into EV progression for this reason. As I said above, you're realistically competing for 1 spot as a Sin DPS. Blame the game design if you have to, but that is the sad truth.
That being said, if you are skilled enough, there's no reason not to take you. I've run with an excellent DPS Sin before and, if he were still playing, would certainly bring him along again. I would not, however, handicap the group by using 3 melee DPS or skipping a Marauder to do so unless there was no other choice or we were on farm content where it really doesn't matter.
First, apologies if I sounded like I was snapping at you. I've had this type of conversation a lot before, mainly in WoW, so I'm quite set in my opinion on it.
I didn't say you didn't know what you were talking about. I could tell from reading your post you were a very..progression oriented raider, and yes in more progression focused guilds I know they take things like group composition a lot more seriously, but my main point on that is that that's not the norm and I don't think it's right to try and convey it that way to someone who might not share your same ideals about end game raiding.
For me, raiding was more about the people I raided with rather than how far we progressed or how fast we did so compared to other guilds. That's not to say I wasn't a good enough player to make it in a more progression focused guild, I simply chose to stick with people I enjoyed playing with, otherwise I just get burned out really quick.
As far as melee vs. ranged I don't really consider that a "bring the class" issue since it encompasses multiple classes and it's more involved with specific fight mechanics. Perfect example of this was Mimiron in Ulduar in WoW. When Ulduar came out my guild put together a core 10 man group which I was the OT for and our focus was to bust through as fast as we could. If I recall we progressed up to Mimiron (10/13 bosses) in about 2 weeks. Unfortunately our core team consisted of almost exclusively melee DPS and Mimiron is pretty much impossible to defeat without some ranged. In that case you're pretty much forced to bring ranged over melee no matter what. Personally I think that's a lame design choice, since you're effectively exclusing/limiting certain players simply because of the class they chose, but that's just my opinion.
As far as 'bloodlust' type buffs, I agree. I remember, again back in Ulduar, we brought a Shaman into our 25 man who had literally just dinged 80 the day before and was still in a lot of quest greens..simply because we didn't have a Shaman on and needed bloodlust. Again I think this is an unfair choice design wise to practically require a specific class simply because of the utility it provides. In certain gimmicky fights it can be ok, but I don't think it's right to have such a general buff that is seen as a requisite to have all the time. I'm not saying classes shouldn't have different utility, or even some having more than others, but having a single ability that's considered so useful someone of that class must be in the raid at all times just seems...wrong, especially in a game like TOR where spots are more limited.
Anyway, this is getting more and more off topic. Feel free to respond if you wish, but I probably won't post anything further. At least not about this.