Yeah, the 3 first entries + KotDP could arguably be considered some of the best RPG.
I wouldn't have PoE2, though the author argument that it's real time or turn-based could be acceptable.
Iratus? I haven't played it, so I can't say for sure, but from what I understand from various reviews, it's not spectacularly better than Darkest Dungeon.
As for Caligula Effect, the only reason I can see is that the list hasn't been made by people who play games but by the marketing dep: even if you wanna have a JRPG on the list, there are so many better choices on GOG: Dragon's Dogma, the Legend of Heroes series, the Ys series...
Crisco1492: If we're pushing a JRPG, I'd definitely put the
Trails in the Sky series over
Caligula. The translation is stellar, the gameplay is fun, and there are so many homages that fans of the genre will probably find a new one every playthrough.
Oh, and Estelle is a great character. Even better than Joshua. Brooding dude with a dark past? Meh, been done. Girl who squees at anything kawaii but still lives up to her father's martial legacy? Sign me up!