Reducing demand for overhead compartment space would actually seem to eliminate the entire reason people want to get on the plane as soon as possible. Apart from needing to jockey for space to store luggage (or, if in first class, get that first free glass of champagne) I don't understand why people are in such a hurry to move from a semi-comfortable waiting area to a completely uncomfortable airplane. The plane is not going to take off any sooner than scheduled, and in my experience it is pretty rare for a flight to be delayed due to slow boarding alone.

I actually have a frequent-flyer status that could get me on the plane very early in the process, but what I usually try to do instead is travel with only one carry-on bag, book an aisle seat, and wait until most everyone else in my 'zone' (presumably including the others in my row) is on the plane before I get in line.