Let me answer a few questions before I start driving this morning.
1. The exclusive use of one type of magic attainment style and of more focused magic styles is the result of cultural influences in the game. The starved magi are rather fanatical, something like the self flagellation groups from the middle ages. They believe their magic is the only "pure" kind and that their self sacrifice is to keep society intact. Bloodskimmers believe in a sort of perverted "Survival of the fittest". They consider themselves to be the new alpha predators who feed on lesser animals and men; that they live by right of superiority and might. etc. There's backstory behind each and it's more then just that particular style that binds them; rather that style is a result of the greater things that bind them.
2.However, it is entirely possible for players to start their own gangs where they mix different methods or even develop their own. The only downside would be that the other gangs are more established; they have npc members, hang outs, resources,knowledge, all that sort of stuff. So while it would be completely possible for a group of players to branch off and create their own gang, gather npc units, amass knowledge and give the others a run for their money, it would be more difficult.
3.Respawning wouldn't really be a thing to worry about. For one, you begin unaffiliated and can live your life as a lone wolf or join a gang or create your own or hell, start a cafe and sell bagels if you want. Secondly, magical knowledge is unique to the character. Dying means losing that knowledge. And, although you can write down that knowledge or teach it to others, it takes time to learn. So it's not like raiding someplace would be impossible because an endless supply of meat shields would keep spawning in some back room somewhere.
4. I'm still working on how magic would work, mostly because I would be creating a new, more holistic system designed around discovery via experimentation rather then being given a list of words and just combining them. That and working on making it a deterministic system yet still one that feels "magical".