For me, the problem came when they decided that bardic magic was its own separate thing from wizard magic. In 2E, bardic magic was just wizard magic that the bard happened to pick up in their travels, which meant that all of the magic in the world came from either the gods or from studying the natural magical forces of the world.
By the time 3E came around, bardic magic was its own thing, and it represented yet another source of supernatural powers. I'd be fine if a setting had musical magic instead of arcane or divine magic, but as you add more and more distinct elements to the setting, it just gets bogged down. A world with one unified source of magic, like in Harry Potter, is just way easier to deal with than a world with twelve different sources of magic.
I'm also not a fan of wizards casting spells all day, either, though. If a wizard only had a handful of spells in a day, and had to rely on hitting things with a staff at some point, then that would be great. And the combination of adding in several different sources of magic, while also letting everyone cast spells all day long without ever running dry, means that magic just completely overwhelms the rest of the setting. There's just too much magic for me to really care anymore.