The issue with this is that there are already long FP lines on the marquee attractions. The majority of folks will want to reserve the same rides multiple times and the system won't be able to handle the capacity.
The issue is that Disney, through advertising, has increased the usage of the fast pass system and underestimated the impact of the increase.
I do agree that they shouldn't start the fast pass windows until one hour after park opening. That allows the RD folks a chance to experience a ride without the lines making it possible to get a second first tier ride into an itinerary without waiting.
Would also like the ability to hop with the fast passes but I think this defeats one of Disney's objectives...which is forecasting park attendance in order to staff most cost effectively. If they limit you to one park, for fast passes your behavior is more predictable. And because you are booking these attractions 2 months ahead, they have a much better ability to predict park attendance and staff accordingly.