This is what I loved about Rikti Mothership Raids. Just sign up, come one, come all. Fun times to be had for everyone, plenty of rewards (especially once incarnate drops came around).
Mothership Raids were one of the few times I ever actually ended up forming teams and leading myself. Those were fun and didn't leave you with people whining and complaining about other people's builds or anything (not to suggest that always happened; I think the community got a lot better about pickup teaming as the game progressed than from when I first started playing around i6 or 7, but I did have enough of those elitist experiences in those early days that turned me off of teaming much of the time.)
Hmmm...how to say this...ok.
I realize that for the most part, how another person builds and plays their character has little to do with my fun, my perspective during an event like an MSR. I think, in retrospect, I probably had some regret, maybe some jealousy. I almost always brought a level 50 to an MSR. Sometimes I led them, and certainly couldn't bring a lower level character for that.
I think it's fair to say that different ATs and powersets can bring something useful to the table. However, when I would see level 5's, sometimes, level 1's, level 10's..well, I have to say, it really bothered me. Probably more than it should have. I had low level characters that could have used some xp. In my head, though, it just seemed to me that it would be unfair. Why should I get this easy xp with a low level character when others are bringing their 50's?
To be truthful, usually, it wasn't an issue. I'd see a low level character and not want them on my team, because below level 20 they just didn't contribute that much. They didn't have that many attacks, that many buffs - they bring less to the table. I'm killing a swarm of Rikti within seconds, and they are getting clobbered every minute, needed a rez or a tp back to the ship. Since you had to be level 35 to even earn a Vanguard Merit, it seemed to me that was where the cutoff should be.
Sometimes, however, particularly after a new powerset went live, we'd have 25 to 30 characters under level 35 and maybe a dozen 50s. When a league can barely defeat the 12th pylon before the shield goes back up, well, that's an indication that something is amiss. It wasn't that much fun seeing half your league defeated in the middle of the bowl. I'm not saying this doesn't happen every now and then to an all level 50 team, but the difference in buffs and debuffs isn't negligible.
On Liberty, I would lead an MSR because @noyjitat would have things come up and not be able to. I was happy to do it, but seeing characters under level 35 always bugged me. I'd make notes as to what their global was, and see if the next week they brought something higher level. Invariably, some people were just really enjoying the new powersets and once they hit 50, they'd keep bringing that character until the next powerset came along. I was okay with that. Some would bring a level 1. One guy wanted to get all his levels from the MSR. He never even trained from the previous MSR. Now, I get that some folks had limited playtime. I understand that not everyone could "pl themselves" with a second account in AE in just a few gaming sessions. I understand that some don't like playing lowbies and really just liked the level 50 action, because, well, that's when you felt powerful. But really? You couldn't have at least trained?
Some folks on the server understood where I was coming from. Others, not so much. In retrospect, I think I wanted to bring the level 1! I didn't care much for the low level action and had much more enjoyment out of the incarnate trials. Aside from the Hollows, Striga and Croatoa, I didn't care much for the content. And really, Striga and Croatoa were awesome compared to the Hollows. But, Frostfire on a team of 8, or Atta - those were epic missions. Lots of xp in those, and I loved those story arc completion bonuses.
It's totally unreasonable for me to think that others should play the way I would. But, that didn't stop me from wishing they would bring a level 35 or higher character to an MSR.