I'm running a Klipsch HD-500 7.2 system in my bedroom with a Denon AVR-3311. The Klipsch HD-500 system is just 5.1, but I picked up two extra speakers and an extra subwoofer on ebay for a very reasonable price. I have less than 400 bucks in the whole speaker system. It sounds great. Those two little subwoofers side by side in my bedroom are fierce. Having the two extra speakers in the back also really helps to better fill the room with music.
I would be careful about turning up the tiny speakers too loud. They will blow. That's why there are always HD-500 grilles for sale on ebay. lol The speakers are sealed. There is no way to repair them, so once they're dead, they're dead. That being said, before I hooked up the HD 500 system to the 3311, I had them hooked up to an old Denon AVR-3802, it was just as powerful, probably a little moreso, than the 3311. I haven't had any issues with the HD-500 speakers with either receiver. You just have to use some common sense.
I upgraded my 3311 to a 4311. I wanted to add front wides to create a 9.1 system in my living room. The 3311 got moved to the bedroom. I have a five year warranty on the 3311. I just couldn't part with it for a few hundred dollars. The 3802 is going into retirement. It has served me well.
You are right though, there is no reason to have that much power to push such tiny speakers. It's like powering a Honda Civic with Jet Fuel. A much smaller receiver would sound just as good except you might not get Audyssey with a smaller, cheaper unit. In which case, unless you paid for a professional installer to calibrate it for you, the smaller unit probably wouldn't sound anywhere near as good.
One last thing. Be sure to set the crossover frequency to 150, like it says in the manual that comes with the HD-500 system. Then they won't have to handle much bass at all.