The whole "i need to get stronger!" thing is getting annoying, yes, but the plot actually moves and after constantly getting beaten by vastly superior foes who dont hesistate to hurt the people you care about, a protaginist who ISNT motivated to get stronger would be fucked up.
Yes, the major difference between Negima and generic shounen is the sheer difference in plot quality.
Bleach - 100+ chapters for an arrancar arc that resolves NOTHING, just "lol we went into there to fight against superior foes and LOL WE GOT TRAPPED LOL"
Naruto - 100+ chapters of "WE NEED TO FIND SASUKE" and one on one face offs with akatsuki members(after the obligatory sasuke team member arc and running aroun finding said akatsuki member arc)