The real issue with Naruto is an equal issue of too many characters, while at the same time making more and more and throwing them everywhere when they're incredibly boring. There's already so much going on and I could care less about anyone introduced in the timeskip, minus the villains and Killer Bee.
That's not an issue at all, it's a JUMP manga. A successful Shonen manga in JUMP always has that same formula. Loads of characters as back up for the main protagonist, character development up to wazoo, Strong hero but has this dark past or a cool secret. Something to do with a lost/dead family member.
The reason they start throwing random characters in certain arcs is based on character popularity.
Hunter X Hunter and Eyeshield21 had (has) LOADS of characters, some no one cared about but the manner of putting them in the story was done well. Bleach is more like a plot convenience.
fuck i read too much manga
I'm aware of massive casts, but Naruto seems to have this bug bad even more than other shonen fighting series. Seriously, I've lost count of the characters that have been introduced, but I can count the ones I give a crap about almost completely on one hand. A bunch of them seem too be there for this big political plot Kishimoto is trying to do, but it doesn't work because it doesn't match the feel of the series at all, plus most of these characters could be removed and chance pretty much nothing at all. That aren't cool or interesting, they just exist as a random cliche and seem to pop up just to move the plot when that job could easily be replaced. I think I would like Naruto way more right now if they went back to the roots of the first series, character focused and somewhat dark, but overall an uplifting series about a few great characters overcoming the odds. This massive political plot's message is heavy handed and just doesn't work.