I don't mind the main trio as you said, though I think another problem of the series (AND CORRECT ME IF I'M WRONG, it's been so long since I read the few volumes that I did) was that it seemed to try & introduce a ton of characters right near the beginning, i.e. in that one pub where they get jobs & such. The problem is it's a pain to remember so many characters at once especially near the beginning if they're not part of the main cast. One Piece, for example, has a HUUUGGGEEE cast, but it's spaced out over the series and each arc, so you get to spend time knowing certain characters, then they move on & time to meet a new group of people. Sure, characters may return, but we tend to spend enough time to remember who they are when they do return.
I think part of my time reading the first few volumes was "wait, who the hell was this?" because it was trying to throw so many characters at once.
Edit: Thinking it over, maybe the intent was trying to show just how big the world was because of how many people were "involved" with the story. Nothing wrong with that, but again, space out how many characters you try to introduce & how long we get to know them.
