Nope. I work for the Service Provider here and we've been running our IPTV service for 5 years now - we were the first in Canada and one of the first in North America to launch our service - we were also the first company in the world to deliver HD over copper over a completely IP-based network (no ATM).

So it is completely possible and feasible - many providers are now taking our lead and developing similar services.
ADSL 2+ technology is adequate enough to offer HD over copper and this fall we're implementing VDSL2 with dual access into the home over 800m loop lengths to deliver 40 Mbps to the customer - plenty of bandwidth for a couple HD sets, other TVs and your High Speed connection. You do require at least ADSL 2+ for HD though - prior to that we were driving 8 Mbps to the home for basic TV and High Speed via ADSL and 1.5 km loop lengths.
In short, IPTV is great and it works!