About a paid service to choose a room before checkin: I don't think
DVC can charge for that.
For 2 (+ 1 bonus) reasons:
1) it's like when they charged parking for cash guests. I think it's written somewhere in the Pos that DVCMC cannot charge owners for services specified in the POS as part of the ownership. The booking system is integral in the system
2) the DVCMC must make decisions in the interest of the membership. Adding a paid service (whose revenues would go to Disney) that would prioritise some paying members over others wouldn't be in the interest of the membership.
If Disney adds the service for cash guests at the hotels and offers it for DVC stays, they would have to give it to owners for free.
The bonus reason is that optics would be bad. Disney rents only 20% of the (declared) DVC resorts for cash, why mess with DVC sales for little return?