Attempting to qualify the legacy of grunge to the 2000’s nu metal dreck, is no different than saying Rage Against the Machine’s legacy is defined by Limp Bizkit or The Beatles legacy is defined by The Monkeez. Woefully shortsighted. The music churned out by major labels in the wake of grunge was a corporate reaction and a desperate attempt to capitalize off the unforeseen success of that movement. I don’t think any other genre should be judged by what was popular in the 10-15 year period immediately following, so doing it here just feels weird. That you attempt to assign this as the legacy of grunge is especially strange given your statement of “the popular stuff is rarely the good stuff.”
And really, when most people reference grunge music, they are talking about 4 bands: Nirvana, Pearl Jam, Soundgarden, and Alice In Chains. Four bands that had very few similarities sonically and whose relationship to one another was mostly based on proximity and a very general aesthetic. Frequently riot grrrl acts are lumped into this, unfortunately and incorrectly.
The assertion that Nirvana “doesn’t deserve nearly the amount of praise that they get” should really be taken up with the endless and ever-growing list of artists that routinely list them as an influence. And that certainly extends from artists in hardcore to heavy metal to hip hop. You might not like them (I don’t really listen to them), but your favorite artists probably do. Obviously this is well beyond just some Gen X love affair, considering the increasingly obvious influence they have on modern punk, hardcore, and rock genres respectively. The legacy of the grunge and riot grrrl movements are still very much being written. Whether you are listening to it or not doesn’t change that.