Could you elaborate what the problem with UEFI is and what the alternatives are? Genuine question, as I've never heard this sentiment before.
It is simple: the mere fact of adding network support at BIOS level remains problematic.
And we are not talking about TFTP, but DHCP and NTP (not to mention even more problematic HTTP[S]) which clearly does not belong at BIOS and should not be at UEFI level.
I've heard many complaints about UEFI. Personally, I don't like the complexity, and I distrust some of the parties involved.