It would to be very useful to have the ability to create simple groups without them being turned into actual model or detail groups (which clutters the project browser, increases the file size and adds another step into the process i.e. naming the groups).
This is a really simple feature that can be found on other packages (like Vectorworks or Archicad) and it speeds up the architect's work. As an example, when doing room layouts by moving a cluster of objects around until an optimal solution is reached but will not be repeated elsewhere.