Why would a puppeteer NOT do this?* I mean, I've been a Sesame Street and Muppet fan for as long as I can remember. I've made paper puppets, real puppets, I tried to teach myself ventriloquism.
But I've also done a lot of acting, writing and directing. I never planned on puppeteering being a career. But the chance, any chance, to audition for the Muppets comes along and I would hate myself for passing that chance up.
If I get bounced at the pingpong ball stage or because my voices aren't good enough or because I'm left-handed, at least, when the opportunity came along, I was there. And not being good enough for the Muppets certainly isn't going to stop me from using puppets in my work.
I've seen it posted many times here, that it is very difficult to get into a Muppet/Sesame audition. They are going to see a lot of puppeteers in a short period of time and are going to have a great selection to choose from in the future. Which will make it even more difficult to be seen by them in the future. Why not go for it now?
Everyone has to make their own decision. And if someone is being completely honest with themselves and know that, right now, they just aren't good enough, then that's respectable.
But if the only thing that is keeping people from going to this audition is fear of failure or fear of success or even fear that the dream of working with the Muppets will end now, well...
*footnote: other than the obvious reasons like too far away, four broken limbs, dog ate my puppet, etc.