You do play as pretty much every other Servant/Master if you do the side shit , so it's not like there's a lack of gameplay as the others but a free mode is as basic a feature as you can get in a Musou game , which this is despite having other systems baked into it.
Fuckers either were under time constrains and had to release it like that or they thought they could squeeze a couple more bucks out of people. Whichever one it is, it's shitty .
I honestly could believe either one if that's the case. As someone who knows Omega Force/Team Ninja/Koei Tecmo, they tend to strive for the best they can when it comes to collab works(Hyrule Warriors, Fire Emblem Warriors, Persona 5 Strikers) but it's Koei Tecmo that are the greedy assholes that tend to basically fuck over everyone's works(Dead or Alive 6 was king of this as Team Ninja tends to make whole new engines for each DOA game... but 6 was different as Koei Tecmo FORCED them to use a modified DW9 Engine because the game bombed... which completely fucked over DOA6).
So I can understand if it was Time Constraints(Especially with the fact that this was supposed to be a Souls-like at first) or it was Koei Tecmo fuckery(because it would not be their first or last time fucking over a development team's work for greed).