I guess the question then becomes why bitcoin still is <1.0.0
I've said the same thing years ago. Originally the "1.0" was a target for whenever "client mode" as planned by Satoshi was implemented, making the Bitcoin Core implementation feature-complete for as a minimum working/viable project.
Ultimately it is not so important and tends to generate a lot of discussion - so maybe we should just do the emacs thing and go from 0.12 to 12.0 for next version.