Multicraft?

Hello, I am planning on purchasing a dedicated server soon. No need to giving me suggestions on that. Anyways I am wondering if I should just purchase a multicraft license for a few servers. I have quite a few questions though.

How many servers should I buy for? I see that with one license you can get a bunch of servers? All for the same price? The servers that will be opened initially are Op pvp, factions, creative, skywars, and of course the hub.
What are the main reasons you shouldn't...

Multicraft?