I think you need to do a little fact checking on your music history there. Blood Sugar Sex Magik wasn't released during the heyday of grunge, it was released just a couple months before grunge popped into the mainstream, during the final moments of the hair band era. Shit like Extreme's "More Than WorRAB" was still dominating the rock airwaves and Nirvana's Nevermind, the album that eventually broke grunge to the world, was released the exact same day as Blood Sugar Sex Magik. Also, it's not as if this time period is when the Chili Peppers first made an appearance, they weren't the biggest band in the world or anything but they had already been around for 8 years by 1991 and had a couple of minor hits, videos on MTV, movie appearances, and a fairly large fanbase.
I was a huge RHCP fan before Blood Sugar Sex Magik. I remeraber how excited I was in the summer of 1991 when I heard they had a new album coming out. The first time I heard it was at a birthday BBQ at my friend's house and I can clearly remeraber how disappointed I was by how much it sucked. Gone was the energy and fun and the funk and punk of their previous four albums and in it's place was some lame approximation of classic rock. Such a bummer. And then, to add insult to injury, the album got huge and on the back of what was easily the worst song they had written up to that point, "Under the Bridge".