The main reason I bought them was the ability to display multiple colors - I absolutely wear that out. I love having a red-colored room when I'm playing video games. Dimmed 'sunset' colors when watching a movie. Party colors when friends are over.
I think they're really fun, sometimes useful.
When I want to remotely control a light switch with my voice, I tell a kid to get up and flip it. It doesn't always work, but I at least know that they understand what I want. And it means that sometimes you have to be the one to flip the switch for someone else.
We have fireTV which offers push button voice commands, my 2yo -- who is a little retarded in his speech -- launched Plex the other day (I said "launch" he said "Plex"). I was, inter alia, impressed it managed to decipher his speech, albeit a single word.
[0]: http://www.craveonline.com/design/1189025-amazon-alexa-doesn...
Even a perfect solution that never screwed up and wasted my time would have to also be very cheap ($100-200 for whole house—yeah, right) and take no time to install/maintain for that to be worth it to me.