I have a nice home theater system too. Not $15k nice, but nicer than most folks and a good start (Denon AVR-X1300W, 2x Pioneer SP-FS52, Pioneer SP-C22, might get a sub soon).
There is something appealing about having audio in every room coming out of a relatively small box that sounds good enough. I'm not going to get a proper amp and stereo speakers for every room - they take up too much space; cost too much; and streaming music to them can be a pain. These wireless speakers are appealing to me because they sound better than pretty much any bluetooth speaker (bluetooth sound quality is terrible as you know), but still have a small footprint and an affordable price.
It seems I can get 2x Sonos Play:1 and 2x Sonos Play:5 on ebay (good condition, used) for under $1000. That's listening to quality tunes everywhere I go in the house, no hassle. With the home theater always there for tv and movie watching, of course.