In this case, the Roman player will find it a bit difficult to "force" anything less than total annexation. Firstly, the Samnites have revolted against Roman rule, and not re-annexing revolters would be a sign of weakness. Secondly, the Senate (not an individual player) makes the decision on all diplomatic offers, so it would take quite a lot of calling of favors to swing the vote.
In the case of a regular war, annexing an enemy state is not necessarily the best option; annexed territory is prone to revolt (i.e., needs to be garrisoned especially during wars), and its troops are rarely very good or reliable (with some exceptions - mostly tribal forces).
Forcing a treaty or a pact on the defeated party may often be more beneficial - a treaty forces them to acknowledge your right in victory (meaning you'll have peace from their side for a while, will keep your relationship at a normal level, and you can still annex some territory and request tribute in the treaty). A pact forces them to become your vassals - which leaves them nominally independent, but allows you to call on them for tribute and allied forces as you will.
There won't be anything resembling EU2's badboy factor. It's not a game mechanism that I think makes sense.
