Love alot about the playtest. Same concerns as many people here, hoping a bunch was cut out to make it playtestable, bones are good, and not feeling adding Level + Proficiency to everything.
It's almost certainly not going to change. It's the kind of deep assumption in the mechanics of the game that doesn't lend itself to change: they built the whole game and possibly their business model on this.
That being said, it is on basically every roll, therefore adjusting it might not break things horribly. So, a potential house rule: instead of a flat adjustment, make the Proficiency modifier a fraction of your level:
Untrained: +(Level x 1/8) (round up!)
Trained: +(Level x 1/4)
Expert: +(Level x 1/2)
Master: +(Level x 3/4)
Legendary: +(Level x 1)
Or something like that. This way you get +1 in a Trained roll every fourth level, +1 in an Expert roll every other level, +1 in a Master roll every level except for every fourth, and +1 in a Legendary roll every level. At 20th level Untrained rolls are only +2 better than at first.
Basically, you'd get better at everything, but the rate at which you get better in things you didn't invest in is slower.