"At least" seems like a very good way of introducing a DoS vector.

I think that 1024 was probably too short as a limit, but I think that it does make sense to impose an arbitrary upper bound to reject malformed requests early.

I don't see what you mean by "the HW vendor's problem", I can assure you that any browser in existence is going to have an issue if you send a 1TB URL, while the NIC will have no issue transmitting it.