There's no need to declare the RAM on a device as long as it can perform the task that it's designed for. You could, for example, give a Roku stick a billion times the RAM that it's got now but, apart from having to pay mega-bucks for it, a user wouldn't be able to notice any difference at all.
Don't allow yourself to fall into the trap of thinking that 'biggest is always best'. For example, camera manufacturers want us to believe that a 100 Megapixel camera is better than a 10 Megapixel camera but, unless you're planning on printing pictures a lot bigger than A4, it isn't. Equally, broadband providers want us all to believe that a 1000 Mbps connection is vastly better than a 10 Mbps one, whereas for people living on their own (who don't download large video files, such as full-length movies) it provides no advantage whatsoever.
Increasing the RAM in an already perfectly-functional streaming device is like putting a Ferrari engine into a car that's never going to be driven outside of a 30mph zone. i.e. there's no point whatsoever in doing it.