The game is better? That is a matter of opinion.
To a certain degree: yes.
1. It is easier for the DM to create monsters.
2. Players can´t guess easily how powerful exactly the monster is.
3. The Dm does not have to apply a strange amount of levels, just because a monste should be able to do x.
But you have a point:
Randomly assigning powers to NPCs of PC races. Or maybe even other humanoids should be carefully considered.
My way of creating 4e NPCs usually involves taking abilities of PC classes and add some generic bonuses that take care of the things PCs would use feats and to a certain extend magic items.
I hope 5e monster advancement system will use class levels. As feats and skills are gained by themes and background, you probably don´t get weird results and you don´t have to worry about assigning skills and feats, just because you used a PC class. The theme would be NPC and the background too.
But I also want not only advancement rules, but modify rules. Take a monster and just add certain abilities of classes. Monster creation should not be limited by adding class levels. If an orc brute had learned whirlwind attack and nothing more, and he is meant to be a shocktrooper that should die after having dealt this damage, i want to do it.
Maybe all the goblin learned in his warrior training was swinging that giant flail wildly around himself. (I am making this up on the fly).
So if a player asks, why the goblin can do the whirlwind trick and he has to wait some more levels, i can reply: "you can learn whirlwind, but you can´t use armor, your hp is only d4 and you only know how to wield an oversized flail in this manner.