For casual viewers, streaming maybe good enough.
One downside of streaming now is that there are very few providers (Netflix is one) who offer lossless audio (Dolby Atmos, dtsX, Dolby TrueHD and dtsHD MA) which HT enthusiasts prefer.
selling point really is convenience.
nothing beats watching or listening want you want at that time you want it.
and you are able to play and manipulate it without even going near your system. that is cool...
quality-wise, for both sound and vision, it still needs some work to do and most of which are actually uncontrollable such as internet speed stability, for example.
i am one of those who decided quality trade-off with convenience and happy that i have done it. i am now currently trying to make the best out of this decision.