Time is pretty irrelevant for versioning, unless you have paying customers and you want to trick some into paying the full price for a minor upgrade (eg. Windows 98, FIFA 2015, etc.)
1.x tends to fulfil the original goals of the project. As long as there are some unfulfilled goals, it's still 0.x. 2.x, 3.x, etc. are breaking changes, often a rewrite.
One reason we're not at 1.0 yet is because the original 1.0 goal was to have complete SVG 1.1 support in, which will likely never happen. We changed the version numbering scheme to better reflect where we think we are.
The reason why we're still not there right now is because there are some essential things like canvas coordinates, fixed "flow text" support (so it works in browsers), etc that we need to rectify first before we're comfortable with 1.0.
As a long term user I'd agree to some extent, the 1.0 version feel has definitely been and gone - probably I'd say this is about a version 4, to my mind.
http://wiki.inkscape.org/wiki/index.php/InkscapeInvariants are the stated aims of the project and AFAICT they've not achieved the SVG spec compliance completely yet. Though I thought I recalled them aiming at the reduced SVG "basic" set (? if that's what it's called) and reaching it.
I've been a user since it forked from SodiPodi (and indeed was a SodiPodi user too).
I miss SodiPodi, with it being multiple-document single-toolbar'ed. Iirc this was the sole contention of the fork- Inkscape was born explicitly to have each document have it's own suite of controls.
No, it was born because of the structure of SodiPodi. Lauris was effectively the gatekeeper and others did not have commit access. He wasn't accepting patches he didn't want to, so a handful of our founders decided to fork and have a much more open approach. As it stands, if you have two patches accepted with the project (Inkscape) and want it, you can have commit access.
1.x tends to fulfil the original goals of the project. As long as there are some unfulfilled goals, it's still 0.x. 2.x, 3.x, etc. are breaking changes, often a rewrite.