I don't know if I agree with you all.
When you go to change a reservation, and you want something new that you didn't have reserved before, you are not necessarily entitled to 'hold' a room that could be booked by someone else. It is your limitation that you don't have enough points for two bookings. The system is built on first come first served, so if someone else already had a waitlist for part of what you are looking at, or your previously booked reservation disappears because you in effect gave it up to try to get something else, that's a chance you are taking.
Changing a reservation is a chance you take. I've had a reservation disappear when trying to change. So I know the feeling.
The other thing I will mention is that the waitlist works to a certain degree. Expecting it to work for week long vacations may be a bit much but for a night here and there, the waitlist is a great tool.