Not to mention the amount of features they'd have to remove in order to comply with Apple's standards.

Would its plugin / scripting library even be allowed? I don't know the specifics of the OSX app store rules.

Based on BBEdit, which does have a version in the App Store, the plugins and scripting would be just fine -- but the CLI integration wouldn't be. (Although you could probably download it separately.)

I don't really see what the advantage of putting ST in the App Store would be, though, for either its developer or any of the users. I like the App Store well enough for certain things, but for developer tools and many utilities the sandboxing tends to be an annoyance at best.

(Also, I don't like that the App Store makes upgrade pricing completely impossible, but that's a whole different rant.)

Yeah, there's really no incentive for them do it aside from accepting non-Paypal customers.

paypal accepts transactions without accounts just cards...

Not if it's the same card used on a limited PayPal account :)