I have a Chromecast as well and—prior to purchasing the Roku—used that when I traveled.
The reason I replaced it was because of the purpose it was designed to serve and how I was using it. A Chromecast is a remote viewport, not generally a consumer (save for Chrome and a handful of mobile apps). Take, for example, when I used Plex. I'd have my machine as the Plex server, my phone as the Plex consumer / controller, and the Chromecast as the viewport. All three would be on a private network served up from my travel router, disconnected from the WAN (hotel internet paranoia). All three of my internet-connected devices were required to make this setup work.
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Just remembered the requirement that the LAN be connected to the internet to use a Chromecast. When I'm streaming from Plex, I don't need to be on the internet. Getting connected just so I could then use Plex felt like an unnecessary hurdle.
end edit
Contrast that with the Roku which is not only the viewport but also the consumer / controller. It freed up my phone to remain on the cellular network. I could pass out watching a movie and not have to worry about missing "important" late night notifications / emails.
The alternative was to stream my screen to the Chromecast, but I found that to have tons of lag / frame-skipping.
The reason I replaced it was because of the purpose it was designed to serve and how I was using it. A Chromecast is a remote viewport, not generally a consumer (save for Chrome and a handful of mobile apps). Take, for example, when I used Plex. I'd have my machine as the Plex server, my phone as the Plex consumer / controller, and the Chromecast as the viewport. All three would be on a private network served up from my travel router, disconnected from the WAN (hotel internet paranoia). All three of my internet-connected devices were required to make this setup work.
edit
Just remembered the requirement that the LAN be connected to the internet to use a Chromecast. When I'm streaming from Plex, I don't need to be on the internet. Getting connected just so I could then use Plex felt like an unnecessary hurdle.
end edit
Contrast that with the Roku which is not only the viewport but also the consumer / controller. It freed up my phone to remain on the cellular network. I could pass out watching a movie and not have to worry about missing "important" late night notifications / emails.
The alternative was to stream my screen to the Chromecast, but I found that to have tons of lag / frame-skipping.
Admittedly, it's a very particular concern. <g>