If someone decides to make a minimenu like simplified DE at some future point, no problem.
However, for at least the first wave or 3 of Pyras coming out, having XFCE as a default makes more sense. As new & newb users ask questions of, "How do I XYZ?", having a known default enables the community to help them by saying, "click on P then D then Q" rather than having to ask, "What is your DE?", to which the new & newb would reply, "What's a DE?"
Worse is if the community replies with a pile of code to be entered into a shell (normal Linux forum response) instead of point & click specific to the Pyra's default DE. For better or worse, the world is full of people who see entering text commands as something to be feared but are perfectly willing to click on pretty icons without concern over what they actually do.
So, from a support and community cohesion aspect, keep the default installed software model simple. Debian with XFCE as default.