Hurray, a single player game that is actually great! Though yes, multiplayer does make things better, but single player like Disgaea 5 (and the upcoming Fallout 4), do hold lots of incentives to play without requiring multiplayer.
this is probably the first Disgaea with a legit multiNetherworlds sized war, the most exciting and epic story scenario in the whole series!
No loud immature kid running the show, no former badass turned flakey sardine addict leading the pack.
There’s a whole alliance of (mostly adult) big cheeses this time, and the scale of the conflict is bigger than ever. 
And what’s more, looks like like D2 or I think DD2, there is a early unlockable option to play as any character, class and monster.
https://www.youtube.com/watch?v=ycxOtYSEkK0
This is phenomenol!! They should of had this feature since the beginning. It’s the next best thing to character creation.
Well at least that’s one more single player game that has no shortage of things to do, and it isn’t even an mmorpg.
Though of course, grindy things like SRPGs, shouldn’t be picked up too much (it’s ok to skip spinoffs), but I haven’t played one since Disgaea 4,
so Disgaea 5 arriving now is great timing and looks to have the best things about the series, and introduces better things than what its predecessors have done. It’s nice the devs think bigger and better this time.