Do we really need the Mini Display Port on Surface?

I don't get it. The Windows RT version and the Windows 8 Pro version come with an HDMI output that can put out up to 1080p video.

Then why the heck is Microsoft Surface RT barred from putting out a clear 1080p signal of what is happening on the screen? It really bothers me because I will base my decision on whether or not I will buy a Surface on whether it will be able to output to a computer monitor because I can't possibly type starring at a 10" screen for more than an hour.

So, what on earth is Microsoft thinking?