@David Gwyer -
I can’t see us ever even contemplating providing a guarantee of backwards compatibility. It is time consuming enough just keeping up with the latest version!

Thats why having 3 versions a year is an issue. It provides a huge "barrier to entry" for many plugin developers, and we have thousands of abandoned plugins that don't work with the latest release. This in turn stops people from upgrading because the plugin they use doesn't work. It's a Chicken and Egg scenario.

people should ‘always’ upgrade to the latest version for the latest bug/security fixes alone,

No, no, no, no, no.
Thats a simply terrible idea, thats become some form of Rhetoric around the Wordpress community over the 18 months.

You should evaluate the pro's and con's of upgrading ANY software before you do it, and not just upgrade on blind faith. We lost the trust-us/blind-faith argument with Capital_P_Dangit. (adding code a few hours before packaging for release, after the testing procedure was complete and without opening a Trac ticket so people could see it).

There needs to be a business case to support upgrading. We've stopped trying to educate people as to the positives of upgrading, and instead have moved into tub-thumping "ZOMG THE SECOND A NEW VERSION COMES THE OLD VERSION IS SUDDENLY UNSECURE. UPGRADE OF THE EVIL PEOPLE WILL GET YOU. Forward this warning to 10 people in the next 5 minutes or you'll morph into a drupal install".

3.2.1 has no known security bugs, that won't change the day 3.3 comes out. We need to accentuate the GOOD reasons to upgrade rather than the BAD reasons. By packaging Security, Functionality and UI changes into the one release, many of our/my clients live in fear of a security hole being found in WordPress because their AdminUI will change - again.

If your company uses WindowsXP and IE7, or uses bbPress, or has colour blind people, or people that don't use a mouse (hover menus suck), then upgrading to WordPress3.3 will give them a negative RoI.

We've stopped trying to solve WHY people don't upgrade, and are moving to try and FORCE them to upgrade because WE want them to.

I don't know about you, but how's that worked out for Microsoft on IE6 and XP? Yeah, thats what I thought. It's great to be leading edge, but when you're bleeding edge, you start to push more and more people into a category with no realistic upgrade path.

* Using IE6? can't upgrade
* Using IE7? probably can't upgrade (definitely shouldn't)
* Using a PHP version less than 5.2? can't upgrade
* Using a MySQL version less than5? can't upgrade
* Using a MySQL equivalent? can't upgrade
* Using WindowsXP? probably can't upgrade (definitely shouldn't)
* Don't use a mouse? can't upgrade to 3.3
* Colour blindness? Can't upgrade
* Using bbPress? Can't upgrade
* Using a plugin thats been abandoned? can't Upgrade
* Using a theme thats been abandoned? can't Upgrade

Outside of North America, sorry some of us are, IE6 & 7 have a combined market share greater than Opera, Safari and Mobile Browsers combined. This number grows substantially once you move to larger corporations, who are less agile.

We have to stop thinking that we can bend the IT world to our will. We have to stop living in this bubble. Look at the stats in question. 50% of people still on a version 2 releases old. Something in the "THOU SHALT DO WHAT WE SAY" model isn't working, y'know, like it's not worked for any tech company since, well, since we had tech slightly more advanced than then catapult!!

We need to stop thinking like developers and people who knows the system. We need to start thinking like it's our parents who have a WordPress install, and you'll see that people stick with what works until it doesn't work anymore. People don't want the latest and greatest, people want what works.

We also need to stop taking stats from WordPress.com. It's a self hosted blogging platform, that while awesome, is not indicative of the rest of the internet. We're skewing data from 1 source with 1 purpose and making generalisations about multiple sources with multiple purposes from it. It's just a stupid thing to do; and each of you here are better than that (I'm probably the dumbest person in this conversation).

Put down the Kool-Aid, stop building blogs, start looking at the market that WordPress doesn't appeal to but could easily dominate, think like your parent and not a wordpress fan.