None of this is due to any limitation of Linux as a platform. Google can very easily create a client for Linux. Other players are doing so. HBO and Amazon can use modern technologies like HTML5 and expand their user-base. Netflix and Hulu are doing so.
Will the situation change one day? Maybe? Ironically enough, thanks to Google's Chrome, Linux users are able to access many services.
Currently Canonical is the only player who has invested, and continues to invest, in the desktop while biggies like RedHat and SUSE have washed their hands of ‘consumer’ or desktop Linux and focus solely on the enterprise segment. Google has managed to convince players like Adobe to bring their software to Chrome OS, even if it may have a smaller market than Ubuntu.
Canonical may need to learn the art of collaborating with such players. Or maybe Canonical doesn’t see much potential in the desktop space. Meanwhile, both Apple and Google are extremely eager to exploit the golden opportunity presented by Windows' declining market share.
Canonical could have exploited the situation and grabbed the market share. They seemed to have missed the bus. Unless there is a market that Canonical can show to biggies like Adobe, they are not bringing their tools to Linux users.
The twist in the story is that when I am on my Mac, editing some images or working on videos, I run a Linux system either in a virtualbox or x-forward the ssh session from my local Linux server, because Mac OS X simply doesn't have the best of the breed apps and tools that Linux has.