I don’t remember dragon warrior 2 being that bad. Maybe it’s a ROM issue, maybe young me was more comfortable with a constant grind.
3 is special. It shows it’s age, but it’s very very good.
4 is a little more uneven, but I think it’s the first RPG to change your perspective/main character across the story. Also it has the best story of any JRPG I have ever played.
I think the later DQs are enjoyable, but they feel stagnant.
It’s my problem with many games. Rarely does something new come along. This is likely a function of age alongside growing up when video games were new and completely different ideas and genres were formed. There is still innovation, but I feel JRPGs haven’t had anything new in a long time.