The DMC Anime is a big part of the "not much of that". Dante, Lady, and Trish could magically tell when a demon was wearing a human skin, except it was selective. Dante didn't think Brad was a demon in Episode 3 until he confessed, and he couldn't tell King was the woman who hired him in that poker episode. Lady didn't know the priest that sent her after Trish was a demon until he revealed himself. Dante didn't do a single thing against Sid and he was shady from day one and acting like a bootleg Arkham. Like the writers vaguely registered Dante clocking Trish as a demon within a minute of DMC1's prologue cutscene but then forgot to be consistent and didn't bother to explain the mechanics of why demons choose human forms as opposed to disguising themselves as, IDK, a dog or something. And there's no limit to it; demons can just do that whenever they want.
There would be a really good body-snatching plot in there where a crafty demon king sends his army to stealthily replace the human population to the point it can't be solved by just killing really obvious targets. Dante doesn't shoot "humans" or "people not proven to be demons", and he's not very proactive about much, so that's a weakness waiting to be exploited.
Mundus acting as a human prisoner would be interesting, though. I like that.
Things from the reboot being applied to Devil May Cry V has nothing to do with DMCs 4 and 1 and doesn't mean it retroactively applies to any of the DMCs in classic continuity because they were never made with the reboot in mind. Stop applying them like it does, and stop your obsession with my Premium status. You sound jealous and need serious help for that You problem.