It's because tons of unsexy companies had tried doing it the other way, to the point where so many companies have done it that it's started to leave a bad taste in peoples mouth.
People are starting to get into the whole, we aren't sexy but we are solving meaningful problems thing lately.
I think there's also a certain amount of marketing. You don't want everything to be "sexy"; you want some things to be boring, unnoticed, and just work. Saying you're making shipping sexy is just saying "we're going to ignore the core logistics of reliably getting your stuff where it's going as quickly as possible", which is going to scare away customers.
People are starting to get into the whole, we aren't sexy but we are solving meaningful problems thing lately.