As most of the other posters have said, Locked leveling adds a bit of challenge and meaning to the game that you just won't get with infinite. Especially when, as with Oblivion and Fallout 4, the enemies constantly level alongside you. It gives a feeling of pointlessness to the whole thing--why should I spend all this time trying to level up my character, when the difficulty will never change?
That raider you fought at level one is still going to be just as challenging to you at level three hundred and forty two as he was when you started. That isn't fun, that's lazy--and I would even go so far as to say its even worse than not having levels at all. At least in that scenario, your character can gain power through armor and weapons, and as anyone who's played an MMO knows when you finally find that legendary weapon you feel like you accomplished something.
Personally, I don't have an issue with maxing out your stats in level locked games. Even in Fallout NV, it was difficult to actually reach 100 in everything unless that was your goal from the beginning, in which case we can say that your Courier actively sought to master everything. You HAVE to work for it, to sacrifice perks and hunt down the skill books and get enough money for the implants. Unlike in infinite leveling where it will just happen eventually.
This is all a moot argument, though. Deep down we all know the next Fallout game is going to remove Special stats, make all perks available from level one, and start you off in a full suit of Power Armor with a story line revolving around finding your wife/dog or something.