There are a lot of jaded people on this site. Just because you have something doesn't mean you need to use it all the time. A lot of times the wife is napping on the couch while I watch TV and using the big guns doesn't make sense. Likewise, who needs it when the grandkids are watching their sponge bob of disney channel drek. Then, it's downright annoying.
How about this as the reason:
The better speakers were purchased because they are more intelligible. This means that you can hear the audio produced more distinctly at lower audio levels when they are in use.
It means, that the more simple shows, such as the news, won't need to be blaring for there to be proper intelligibility for the person who is speaking.
Likewise, for kids shows, instead of having to crank up Spongebob to understand what he is saying, the volume can be kept lower, and the kids will be able to hear what is going on.
Of course, I do recommend a remote and receiver which offers the ability to have sound presets which can keep a subwoofer from playing at movie levels.
But, beyond that, isn't the entire point of the audio system to get better audio? And if it is in a family room, why not let the family use it all the time so that they all benefit, all the time, from the quality of sound that the nicer speakers recreate.
I've tried it both ways, but my wife and brother both are currently just using TV speakers to watch things and they think it sucks. (two separate homes) For just the stupid shows, yes, you can do whatever you want, but wasn't the point of all this to get better sound? Not just better sound when you are listening?