>With adequately modern browsers being available for Linux/*BSD/etc and XP, and being free, faster, better and more secure, you don't have to have any sympathy for users sticking to old IE versions.
Sure you do, when you want to have happy users. If even a minority of your users are older/non-technical, asking them to change browsers to view your site (which they may be required to use for work) is a great way to get them to hate the damn application, provided they can even figure out how to change browsers in the first place. It makes complete sense as a designer/anyone concerned about security to force people to update their browsers, but don't forget that to the 60 year old used-to-snail-mail grandma that can totally ruin the experience.
Actually that's when you can absolutely getting away with requiring them to change browser!
Except if you meant to write "UNLESS if it is required by someone to do their job".
Huh? Where did you get that impression?
If your service is valuable (instead of, say, just some news site fighting for eyeballs) you can pretty much demand users to use a modern browser.
Even more so, of course, for enterprise and hosted applications, where you can specify what browser the users have to use, take it or leave it. I work on a device front-end that supports all but IE, and it's very liberating -- not to mention no customer ever cared about it enough to complain, they just switched to what he told them to use (and most were using such browsers already).
Also for open source. E.g something like Wordpress (which is used very much professionally) can use it for its admin interface, and require it's users to use a compatible browser -- and nobody will care for the few that don't want to use Chrome/FF/Safari/IE10/Chrome Frame.
With adequately modern browsers being available for Linux/*BSD/etc and XP, and being free, faster, better and more secure, you don't have to have any sympathy for users sticking to old IE versions.
And it's not like you'll be alone in it. I remember when the first web shops started ditching IE6 circa 2008-9 (with a "A list apart" manifesto and everything). That was a huge step forward. And isn't jQuery ditching old IE in version 2.0? Not to mention widely succesful projects like D3 that never supported IE to begin with.