In OP's defense, I checked out both movies' Letterboxd ratings, and Blade 1 is rated at 3.5 out of 5, and Blade 2 is sitting at 3.3, so maybe it is just an echo chamber thing. That being said, I really believe this was not the case 10, 15 years ago.

Having sat with it for awhile now, I'm kind of coming around on the notion. I'd have to do a back to back viewing to confirm, but my current hypothesis is that Blade 1 is an excellent urban action-horror picture. It does everything you'd expect it to do pretty well. Blade 2, being a product of Guillermo's interests, has this weird, quasi-Shakespearian family drama between Nomac, lady vampire, and the patriarch serving as the emotional spine of the picture. It's fine, but I remember a lot more about their dynamics than I remember about Blade's arc, which is maybe not what you want from a Blade movie. Plus, all the extra vampire lore and whatnot makes the picture feel less like urban action-horror and more like a fantasy film, which just so happens to have guns and the occasional unwitting human. Not bad, but it does feel like a dry run for ideas Guillermo would do better in other movies.