often either acting out of curiosity (what's it like?) or ego (I can meditate like a badass.)

I definitely think this is true. Another thing that can drive people is covetousness for an end state that the practices are supposed to bring you--which, of course, is as anti-Buddhist a mindset as you can get.

Your first feeling of your senses spreading out sounds lovely.

Nice nonattachment example at the end of the post :-)