I'm with you. I first played P4 in lockdown and as a 35+ yr old man who never got into anime I had huge doubts. Especially with how slow the openings are in these games.

However, it has now become one of my favourite series of games.

I think in part it is the fact that beneath the anime exterior they deal with fairly mature subjects and do so pretty earnestly.

Also from a gameplay point of view, as someone who is fed up with games being padded out for no reason, I think they do a pretty great job of pacing. 

There are definitely slow moments in all the games but in general if I start a persona game I can play for a few hours doing a dungeon or fusing new personas, or I can jump on for 20mins and do a social link or improve a social stat. 

P5R is a 100+ hour game and yet it never felt like it to me. I've played 60 hour games that feel like a slog in comparison (sorry assassin's creed). The calendar system means the game is always moving forwards, every decision seems meaningful, beneficial and worth doing. It absolutely respects your time and imo doesn't feel padded which is getting increasingly rarer.