This game doesn’t fit a P2P model in any shape or form. Why would you want to pay a monthly sub for a game that can be digested from start to finish within a few hours. What is being online with hosted servers going to add to that?
There are games with far more to them in terms of systems and content also with vastly higher degrees of polish and refinement (see D3, PoE, etc) that are not P2P and offer regular content updates and servers. The reason that this game is not built that way is that it was not intended to be ‘that game’. If you are looking for ‘that game’ there are a number of very good games that fill that niche that you have lucked out on and don’t even have to pay the monthly fee that you seem so ready to hand over. If you are determined to pay someone a monthly fee there is even the sub-par Devilian for which you can purchase Patron status.