As indicated earlier, I agree with Morbus' statement. For developers, 4.7.0 is a significant change. For users, it is not. Calling something 5.0.0 sets a lot of expectations. For the average user, an improved default core theme, written in two days, is much more exciting than the forms API we have been working on for many months.
For the next release, I want to us to introduce a dashboard, create a new default core theme, reorganize the administration pages, and hopefully include an install system. By doing so, we have all the ingredients it takes to release a 5.0.0 and to live up people's expectations.
I hear you, and agree with your reasoning. But, there is another side to release numbers. Release numbers that are close are thought to be more similar, compatible, ...etc. By making numbers close, we fool people (unintentionally of course) into running 4.5 modules on 4.6 ("It can't be that different, can it?"), then they ask in the forums or send emails to developers when things break. With 4.7 we have made it worse. Not disputing your points, they are totally valid, but there is another angle that I wanted to share.