Have you ever had a problem with one of those older, shittier browsers (you know the ones I mean) and you've asked for help on a forum, and been given the helpful answer of "Just tell the client to update their browser"? I know I have, and it's the sort of reponse that just makes me want to kick the person giving the answer square in the Balls. HARD.
Why? I'm guessing that most of the folks who make these statements either work for cool funky agencies that are all "web 2.0" and just do funky brochureware crap, or that they've only ever worked with fairly small companies. If you've ever worked with a large company (and I'm talking 1000's+ of staff, possibly spread worldwide here) you'll know what a laughable idea it is to try and get them all to update their browsers.
In large corporate IT, you tend to get everyone standardised on similar kit. Because of the cost of upgrading 1000's of PCs (in man hours as well as software licenses), a lot of these companies don't upgrade their software unless there's a compelling business reason to. Installing the latest version of SQL Server because it's 10x faster and can run on less hardware, saving the company X thousand a year in hostiong costs is a compelling reason for them to spend money. Tieing up their IT department upgrading everyone to IE9, plus all the training and increased support times as clueless users call tech support because the buttons are in different places, just so you can have rounded boxes and drop shadows when you browse the web is a far less convincing argument.
Another factor is that of Compliance. Big companies have to comply with all sorts of tedious regulations, especially if they work in the financial sector, which makes upgrading stuff even harder, as you have to go through innumerable audits to make sure that the new stuff is still compliant with internal policies and procedures.
Two of the largest companies I work with at the moment are pretty much all on Windows XP with IE6, with the exception of the upper echelons of management, who always seem to have the shiniest kit. It's not ideal, but it's how they operate.
As a web developer, I just have to live with this. I might not be happy about it, but if I want to work with the big boys, I have to accept that that's the way it is, and me asking them to upgrade their browsers isn't going to make it happen (no matter how much I'd like it to)!
Consequently for most clients in this situation, I go for an approach of progressive enhancement (Google it for lots of exciting resources on the subject). We make sure that the site works nicely in IE6, IE everything looks as nice as we can get it, and then we have progressive updates for users with better browsers. That way the poor schmoes at corporate HQ get a perfectly functional website that is perfectly usable, but eveyone else gets nice gradient fills and curved tab boxes!
So, next time you see someone talking about IE6 browser bugs, think before you tell them to update their browsers!