I'm well aware how good Smells like teen spirit is as it was written by my favourite band. Nu Metal had its moments and it gave us brilliant bands such as Korn, Deftones, Slipknot and Limp Bizkit (fight me). Of course for every Deftones you got a Coal Chamber but you get that with every scene. I think you underestimate just how big Freak on a leash is, especially in America.
Fair enough, we all like what we like, but.... and im about to go full music snob here...
Limp Bizkit are legitimately one of the worst groups in any genre of music to ever exist with the absolute worst frontman ever who couldn't rap or sing to save his life and was responsible along with Jonathan Davis for some of the most hilariously cringeworthy lyrics that have ever been penned. Wes Borland was a talented guitarist though, talent that was completely wasted in a nu metal group.
Deftones were and still are pretty good but they were smart enough to dissasociate themselves from Nu Metal pretty much straight away as they saw it for the train wreck of puberty ridden cringe that it was. This is why they have generally outlasted most nu metal groups and are still viewed as credible.
Slipknot was what all the 'pretend to harm myself' melts at the local youth club listened to along with coal chamber, talented musicians but again... unbelievable levels of cringe, especially their token DJ which was the in thing back in the late 90s for nu metal.
Korn were just Korn, they were at least original when they first came out in the early 90s but they had gone fully down the commercial nu metal bandwagon route by the time the third LP came out, it was like their first 2 albums but sanitised and made more consumable to the masses (like limp bizkit after the first lp). The rawness of the first two LPs was gone, instead we got an over produced mainstream record designed to shift units at the peak of their fame.
Nu metal is best forgotten imo and is widely viewed in the metal scene as a big dirty stain on it's history. Please note I don't particularly care for traditional metal either so im not some metal snob... only 'metal(ish)' bands I can stomach listening to nowadays are Deftones and Tool.
Either way grunge will for the most part be looked back upon favourably, Nu Metal won't be... its when dude bro's got into metal and tried making it cool, metals not meant to be cool.