Maybe it's just that we've all gotten to an age where anything we hear, we just blow off as already been done rather than consider it something new. I mean any of the electronic music over the decades, if it didn't resonate with you, could be blown off as "well Kraftwerk was already doing that in the 70s", so it doesn't count.
I think a lot of it boils down to the degree
of change in "something new." To take your example, there was electronic music before Kraftwerk. But, they changed it from a more academic/experimental emphasis to a more pop/dance context. To me, that's a significant enough difference that I felt they truly created a new genre. But also to your point, I don't think it get the "electro" name until other musicians started doing it, because they wanted to put a label on it instead of just saying "I sound like Kraftwerk"
. I also think trance is a legit example of a new genre, but others might see it as not all that different from techno. Then there are the people who say "all blues sounds the same" or "all EDM sounds the same," and don't see any differences unless they are strikingly huge.
So I guess a lot of it is in the eye of the beholder. I'm looking for a big change, something radically different. Then again I'm a music junkie, so I'm always looking for a stronger high