Err isn't the new tower construction due some time soon.
Maybe and this is just a gut feeling.
The amount/access to parking might be reduced due to construction materials/equipment.
The real reason for PPR my ATCO friends inform me is so they have a strip already loaded up for when you arrive so they don't have to scribble like a swine. I also presume the new tower will more than likely be electronic strips which are an even bigger pain in the ring to create a strip while doing all the other good stuff keeping aircraft apart.
I would disagree that filing a flightplan is PPR. PPR is between you and the airfield operator nothing to do with euro control. They would be quite within thier rights to refuse you, flight plan filed, SB informed, immigration informed the works.