Sure, that is fair. I probably didn't word it correctly. I mean if you keep repeating that it is "unsexy" people will probably believe it to be true. Why choose to send that message instead of hey we are this sexy logistics company? It's a minor detail, so I don't mean to make too big of a deal out of it. Just seems odd.
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.
I have no idea how they see it, but I would like to point out that they're not the first to intentionally market themselves that way. UPS used the slogan "What can brown do for you?" for a while. Interestingly, they're in a related space.