There is always some conflict in the X-Men, and that's what keeps them interesting. Mostly the conflict is that mutants aren't accepted by humanity. This dilemma is quite compelling: society isn't willing to accept that others are more powerful and therefore hate and hunt them. This also gives us Sentinels which I guess could count as rogues but are too numerous and all the same.
The X-Men can also never get along. The team is very diverse and very good at holding grudges. They aren't exactly leaping to each others aid either. They all like to talk about what just happened and blame others for it. I think that is interesting because the X-Men usually have a decent writer so the arguments and discussions are sharp and good points are made.
People rag on Cyclops a lot but his is the same situation that Jack Shepherd was in on Lost. He is a natural born leader who is a little too stuck up for his own good. That does provide some conflict though. Cyclops is a good character in the time between battles, making amends and keeping people calm.
The merry mutants don't need a rogues gallery as long as they keep bickering. The stories are interesting and suspenseful even with just themselves as bad guys.
