I disagree. Or at least, you will cause problems for other people. One of my coworkers was delivered a Windows app by a third party - it was written using MFC. I said, "Seriously? In 2010, MFC? MFC was bad even before it became obsolete." My coworker said, "They used it once before and decided it works for them, so that's what they use."
Here's the thing: part of being a developer is keeping up to date. If you find one thing that works for you and don't ever update you are not doing your job.
Learning all the intricacies of a framework takes a lot of time. Once a time, I was all for learning new things, but guess what: I discovered that old tools still delivered.
Sometimes the less dependencies factor matters too. Having to quickly develop a diagnostic application for users to download, a couple of years ago, guess what I chose: Visual Basic 6. Right, that ancient tool. No matter what, the application was easy to develop and the executable was a few kilobytes, with no requirements other than Windows 2000 SP4.
That's great in theory but once an application becomes big and settled it is usually too big to just 'upgrade'. Upgrading becomes a massive time sink and when there's other deadlines pressing for stuff that your clients will actually notice then upgrading won't happen. Ballmer wants to release a new VS every 18 months.
Just skip every other major release and save yourself 1/2 the pain and effort.
