Re: Let me be the first to say...
Oooh, how very 20 years ago of you.
I remember when Netscape started wresting market share from Mosaic (and whoever else there was back then) - suddenly I started seeing sites that were blacked out if Netscape was detected, apart from a little box stating "This site is Netscape crippled", usually followed by a rant on the site owner's part about everything that was wrong about the aforementioned browser.
Most of these sites I stopped bothering with - although a few were useful for my university work, so would use Mosaic for them and Netscape for everything else.
Now, this was also the same sort of time that it was trendy to have a hit counter on your site. And I very quickly noticed that on the few "Netscape crippled" sites I did continue to bother with, there was a dramatic drop in the rate said hit counters increased by following their being blacked out for Netscape.
@AlbertH - you've given us figures stating that the number of IE-using visitors to your sites has dropped to under 3%. But this is kind of like Microsoft's trick with Windows Phones - "we've shipped X thousand handsets... but we're not going to tell you how many we've actually sold". So what about your overall visitor figures - how have they changed since you've added these warnings about "defective" browsers and "insecure" operating systems?
Personally, if I saw a warning on a website worded in the manner you've given, I'd drop the site like a hot potato, as that sort of message makes me think "they're trying to make me scared and trick me into downloading something that turns out to be a load of spyware".
... or is this (and I suspect this purely because of the heavy uses phrasing like "Internot Exploiter", "defective", "operating system" in quotes, etc) just an excuse to have a rant "because it's Microsoft"?
(For the record, I'm a web developer, and would be the first to cheer if IE was removed from the face of the earth).