The MIT license only requires that derivative works are provided under the same license; it doesn't require any kind of attribution.
On the moral side of the argument, I can empathize with both sides: I do appreciate (voluntarily) being credited when someone releases a minor adaptation of something I made, but I'd also don't see a reason why creators should have to put in explicit credits for every detail they copied from me. If attribution becomes an absolute social norm, it loses all its value to me personally...