Kind of agree. Music should be the main reason you want to go.
Glastonbury is so big though, you can easily have an amazing week without seeing any of the main bands on the Pyramid or Other Stage. It's a cracking party, atmosphere everywhere is brilliant. My brother spent a lot of time in the Circus tent and the surrounding area when we went whilst I spent lots of time in the jazz and folk tents. I saw a few of the big bands but Glastonbury isn't about the music at all. It's almost as it's an afterthought. Because of this, it's the best festival in the World!
I'm not going this year, can't afford it but hope to go again in the next couple of years.