I think it's less the fact that the development process is undisciplined, and more the fact that it is just a bore to recode something beautiful for people who couldn't care less about it.
I have worked as Head of Development at a 3-person agency, as a Senior Developer and Front-End Architect at Yahoo! and now as Web Architect at a medium-sized company. On all the sites I've worked on (with their varied budgets and development team sizes), dropping support for IE6 would have been putting our desires as developers ahead of those of the users who are still using that browser. In the end, supporting IE6 actually wasn't that hard; you just have to control what "support" means.
Yahoo!'s Graded Browser Support gets this right. Though it no longer explicitly categorises the browsers it lists into A- and C-Grade, those grades still exist. Rather than Yahoo! prescribing which browsers should get the full experience and which should get a core experience, they leave it up to you:
> The GBS focuses on specifying which browsers need a verified usable experience based on factors such as market share and influence. Defining what is “usable” and specifiying acceptable levels of degradation are left for teams to decide.
From http://www.yuiblog.com/blog/2011/07/12/gbs-update/
That's not to say the GBS is perfect. Using global browser market share may make sense for an international behemoth like Yahoo!, but you really should make your own decisions based on the browsers your users are actually using. Make sure you're looking at unique visitors rather than page hits though, because if a user comes to your homepage and sees an obviously broken layout they're not likely to hang around very long.
In short, supporting IE6 is actually easy if you can justify giving those users just a core experience (minus bells and whistles) and have a development team that knows what they're doing.