There's plenty of us around. It just depends on what you're using the lens for.
Personally, I got mine for shooting paintball games. I'm limited to the sidelines, so I can't "foot zoom" much (at least during tournaments) and the action can happen literally at my feet, or sixty yards away at the opposite corner of the field.
When I bought it, I had just the one body (XT) so carrying two camera/lenses was out of the question, and I wasn't about to be switching lenses out on the field with paint flying every which way. (Besides the fact I'd almost never have the time to do so- games were typically started and over with in less than three minutes.)
Using a tripod was similarly out of the question, and a monopod wasn't much easier.
So all told, I needed a zoom with as wide a range as I could get and IS. The 28-300 does the job quite admirably. Gary of paintballphotography.com uses (and abuses) one as well, with excellent results.
No, it doesn't do everything well, but then, what lens does? Every lens has it's drawbacks and it's strengths. If you need an all-in-one, the 28-300 is a great choice. If you need slightly sharper results or a faster aperature, there are other choices- but ones without the wide range or length. It's all a tradeoff.
Doc.