As a user, I don't like receiving emails like these because they presume some intent that often isn't what I had in mind at the time.

I've gotten mails like this a few times, but in every instance, I didn't forget to complete checkout, I intentionally bailed out for some specific reason (e.g. the shipping charge was way too high).

I suspect some users will report the mails as spam and, if I understand correctly, that could cause issues with delivering future legitimate mail.

Note: I'm not saying that these mails won't work :)