I actually find it much easier to search or browse for content using my tablet or phone, then choose to throw it up on the TV via Chromecast, as opposed to searching for content using a remote like on a Roku or my Xbox.
It just seems easier for me to do this in my hand than ten feet away, especially when I have to try to enter text into a TV interface.
I found Chromecast OK when I was using it by myself, but sharing it is a problem. It's difficult to have two or more people crowded around a smartphone screen deciding what to watch. The big screen interface works much, much better.
Even that aside, my girlfriend doesn't want to use my phone to navigate, so she has to install Netflix on her phone too. And set up the user account there. Multiply that by every service we have (and Amazon Instant isn't on Android)... it's just clunky. Fine, but clunky. Having it all centralised on one box works better, as far as I'm concerned.
It just seems easier for me to do this in my hand than ten feet away, especially when I have to try to enter text into a TV interface.