For all the handwringing, exactly what apps are missing?

What is it that people are trying to with 700000 apps that they can't do right now on RT? Facebook and twitter are baked in... And have the option to take you their site if you need more than the baked in apps provide. Xbox music is iTunes and Spotify rolled into one... Exactly what are reviewers lamenting the lack of other than app volume?

I don't run that many apps on my windows desktops which has millions of programs... Can someone answer what's dearth of apps means when you essentially have the web in hand and a pretty full fledged OS already?