Very convenient!
Do you mean because they only support SMS based 2fa?
Considering they have a drop down menu it's possible they just have not had time to develop the other options?
More than three years seems to me a long development cycle to add TOTP support. Am I being disingenuous to think they just don't care?
That formula would immediately shift if a high profile website registered on Namecheap encounters an SMS hijacking.
The real cost is testing to make sure a code change like this doesn't break existing users and estimating the additional support overhead of dealing with users that lose their two-factor devices.
[1] Seriously the RFC is very straightforward and readable: https://tools.ietf.org/html/rfc6238