You are definitely not stuck with anything on the Metro screen.

This is my Metro UI:

http://windowssecrets.com/forums/attachment.php?attachmentid=31784&d=1341074068&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31784&d=1341074068)

Notice the crowded look of the Start Menu. There used to be as many tiles as installed apps, actually many more because many apps included more than one tile. I can have as many or as few tiles as I want, I can arrange them the way I want. I am definitely not forced to accept tiles I do not want.

And this shows all the apps installed on my Win 8 RP on my Desktop UI:

http://windowssecrets.com/forums/attachment.php?attachmentid=31785&d=1341074120&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31785&d=1341074120)

So you can see you choose how much or how little to show on the Metro UI.

This is my Desktop with the windows minimized:

http://windowssecrets.com/forums/attachment.php?attachmentid=31786&d=1341074348&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31786&d=1341074348)

You can see the Taskbar customized for the way I wish to use it, and the lack of many desktop icons.

A couple of other features of the Metro UI (now understand I do not particularly like the Metro UI and spend almost 100% of my time on the Desktop UI) on the first screen shot, if I right click on the screen a pop up comes up from the bottom showing the All Apps link: (Also note that to access search, you simply start typing anywhere on the Start Menu. You do not need to open a Search box or do anything special, just start typing your search word, etc.)

http://windowssecrets.com/forums/attachment.php?attachmentid=31790&d=1341079336&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31790&d=1341079336)

Clicking on the All Apps link then brings up the All Apps page which indeed shows all the apps installed on my Win 8 RP (these scroll left to right and there are about 3 pages of them. The Metro apps are shown first. All one has to do is to Right Click on an app and select Pin to Start to add a tile for that app to the aforementioned Start Menu. Also take a look at how the app icons are sorted. You can see some of this on the screen shot.

http://windowssecrets.com/forums/attachment.php?attachmentid=31791&d=1341079645&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31791&d=1341079645)

You will also notice several other options including the important Run As Administrator, and even Pin to Taskbar.

Some other things easily found from the Metro UI, place your cursor in the Lower or Upper Right hand corner and bring up the Charms Bar, select Settings (the bottom charm)

http://windowssecrets.com/forums/attachment.php?attachmentid=31792&d=1341080026&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31792&d=1341080026)

Then Select Change PC Settings: (Also notice all the other areas on the settings bar including Control Panel and personalization. Many of these things actually take a user back to the Desktop UI)

http://windowssecrets.com/forums/attachment.php?attachmentid=31793&d=1341080073&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31793&d=1341080073)

The resulting page will give you access to all PC Settings and Personalize settings:

http://windowssecrets.com/forums/attachment.php?attachmentid=31794&d=1341080121&thumb=1 (http://windowssecrets.com/forums/attachment.php?attachmentid=31794&d=1341080121)

Simple, and I don't even use the Metro UI