I like it when larger, more corporate sites go for an informal tone, even if they don't completely nail the humour they might have been striving for. It's a better direction overall than a stuffy PR-speak message, and getting bent out of shape about it just seems like an overreaction.
Obviously they could have written a paragraph of text explaining that, but just saying "something you are using is so old that it is lame (in the duck sense, not in the teenage slang sense), here's how to fix it" gets the job done in one sentence.
This isn't a business website, this is a social network that gets most of their traffic from bands now. I can't fathom how the smallest amount of snark about IE8 being old on a product like this is raising so much anger on the HN community.
Do you think you are in MySpace's target market?
Here is another possible explanation: they aren't some kind of master marketers who unfailingly target their niches and never fail in such attempts.
http://i.imgur.com/DO5Kb.png
And what's with the condescending list? Excuse my vulgarity but the page managed to be insulting, clueless, and factually inaccurate all at the same time. Here's how it reads to me:
a) Fuck you.
b) Fuck you.
c) Yes I do, a big technology company where I can install whatever software I need working on harder technical problems than getting Myspace working cross-browser and I use Opera at home too so fuck you.