In most raids, limiting casters is preferable for a smoother, faster run. The same logic applies to healers: you might bring just one, since that frees up an extra DPS slot. Even better, get a bard that can buff and heal. CC? You don't really neeed CC in most raids, especially at R1. This is especially important in PUGs, where you often don’t know whether the DPS joining are properly geared and/or just running random builds.
I run raids often, I explain to newcomers what to do, tell the party how to beahave in each part even if many know that already, split roles, and often I must do myself boring things like All the jumps and the talk in Skelly, because those who die have no legs most of the time.
People who join the raids are happy beause they know we won't fail and the run will be smoother and faster than elsewhere. Many PM for a spot in advance. As we are fast with so much dps, we can run several raids in a row in a few hours: if possible, during the weekend I try to run pretty much all the raids in the game. Casters? They are limited to 1, max 2, even 0 if we have a lot of dps joining. Yes, also at R1. (LH for ToN and DoV).
If you don’t like this approach, that’s fine: just make your own raid groups and invite whoever you want. That’s your choice. Complaining about how others choose to run their raids won’t help at all. Raid leaders are not there to make charity work. After a work week, I want my raids to be smooth, and for the participants to have a good time. DDO is a game, and in every game there is a meta.
Oh, I don't even mind not being wanted in a group, that's the Party Leaders responsibility and choice after all, but I've always detested players who can't even bother to press the Decline button. Like, why? Why waste my time like that?
J1NG
If you are a caster, I do that too. If during the filling process the main roles are covered, and I know the dps is enough, I just accept a couple of casters from the LFM, so first comes first served. If you want to be declined asap, you will never have a chance to enter. If you are not a caster, I usually decline explaining we already have that role covered.