Well I guess it makes sense because we were getting way too close to 1.0 and we are obvious years away from calling the client "final version" (is it even possible to call it final version ever? It will always keep improving I presume)
Edit: Oh wait I just realized this:
https://bitcoin.org/en/version-history
It looks like the number just keeps increasing. It's confusing because 0.9 looks closer to 1.0 than 0.15 to me.
I understand the never-release-1.0 thing but isnt software made to be always evolving? There is never a final release of a software just because it is 1.0
I mean you can have 1.1 , 1.11 and so and so..
You can.
Satoshi wanted to go to 1.3 in 2010 - from 0.3
edit:
Link: https://bitcointalksearch.org/topic/beta-217
Im not sure if caling Bitcoin 1.3 would be a good idea. 1.0 means usually "final version". If you add additional numbers behind 1.x, that x just means patches that fixes bugs but the final design is already there.
Maybe Satoshi wanted to call it 1.x+ because he wanted Bitcoin to stay as it was for life and additional changes would be just that, bug fixes over the same design (which would mean no blocksize increases btw). Well we will never know what Satoshi exactly wanted, what matters is now and I think 1.x sounds too much like "final version" to me so we might as well keep increasing the 0.x number into infinity.
You can read his thoughts in the link above. In short, he wanted it to "lose the Beta". But then at the end of the thread just figured it would stay at 0.3. This was 2010, remember.