Are we sure about this... At times and given who they are putting in, it would appear to be all about the popular vote! I can see it both ways when it comes to changing the name... or not changing the name.Which is something THEY want to avoid.
Setting purity tests, opens up economic popularity contests I think they would like to avoid.
Genres tend to rise & fall, the HoF is looking to maintain importance no matter what's in vogue.
I think it started as the Rock & Roll HoF for the name recognition, but they want importance of being musically relevant across a few genres.