Indeed.
Something like this has been asked for a few times and will most likely come at some point. would be very useful
I've always thought that when you group items, there should be an option to totally treat them as if they are one item so things like you've described work.
For now, if you have SWS extension installed then you can use an action to force the selected items to fit the time selection which does the job but a manual option would be nice too on the mouse modifiers.
The other way right now is to select all the items and turn them into a subproject which will then treat them as a single item that you can stretch etc and also you can double click to edit as a "subproject".