Not sure if any body else had seen this or is as happy as I am that this has finally been implemented into the Play Store but you can now remove apps perminently from your My Apps list.
Personally I have apps that are from previous devices that I no longer want, use or need and I've always wanted to be able to remove them from the list but now you can.
Simply open the Play Store and tap the downward pointing arrow in the top right of the screen to reach your installed apps, swipe left to reach your All list and on each app you'll see on the right of the apps list a circle with a diagonal line through, tap the for a pop-up asking if you want to remove the particular application. Confirm and it's, awesome.
I'll off the clean my All list up, pic below...