I just hate when a underground artist makes one Mainstream song and their fans wanna turn their back on them(Kendrick Lamar). Well actually Kendrick is mainstream kinda now. Nas is mainstream too, but is one of the greatest rappers in history. Mainstream isn't a bad thing really.
I am all for people trying new things, but I find it kinda lame when a band goes mainstream and forgets their roots. I would rather have people like my music for what I intended to get in to the business for (I mean like my music for the genre I choose to be in), not like my music because when pop is hot, I make pop music, when dance is hot, I make dance music, etc. That is lame to me. If someone changes genres because that is typically what they are known for, okay, but if someone does rock for 40 years and then suddenly starts rapping because it's 'in', that is weak, imo.