As a front-end designer, I'm excited to see the flexible-box model creep into existence. It'd be nice to do a fluid layout without having to do a bunch of workarounds. Excited to know that we'll soon be able to escape the dark past that has been the web (hacks, bloated markup, extra stylesheets, etc). The only thing missing: Microsoft should make browser upgrades mandatory after a certain period of time, as should everyone else. Granted, this may cause some issues but what would the major drawbacks be (extra work for IT depts. doesn't count)?
The backlash for ending support for Windows XP early and getting everyone to upgrade to Vista was huge. Microsoft bowed to all the corporate customer pressure and extended support for XP. Given all the web apps that are made for older browsers, I can imagine a similar backlash easily, though I don't know whether it would be on the same scale. But I can definitely imagine it being enough for Microsoft to back off from such a decision. No harm, no foul is the safest route for Microsoft to go.
Sure it's safe. But that's because people are lazy. Taking your example of web apps for older browsers, shouldn't the teams behind those products be upgrading them anyways or at the very least trying?
When there are better things to do, there are better things to do. When it's not broke, don't fix it. Spolsky's arguments about why Netscape 6 was a bad idea applies very easily to enterprise web apps where code bases have no application outside of that particular organization, and so it's even harder to modify things.
edit: There's something in many corporations called the hurdle rate. All projects have to provide a financial return that is above the hurdle rate. Updating web apps to work on newer browsers does not easily compute to surpassing the hurdle rate because you did nothing to add new functionality/productivity. So it's very hard to get funding for this kind of work in many organizations.
