Gotta say I agree, where is a simple crop option?
I see two ways to accomplish, both with negatives.
There's the Power Tool crop and zoom tool, which (for me anyway) requires some form of zooming. There seems to be no way to just crop unless you can select exactly the same background.. Or you can do the PiP as mentioned, but you can't actually see the 'in video' screen behind your clip. So if I want to zoom way in on a clip, I have no idea how it's centered in the output without a lot of trial and error.
Am I missing anything?