Other than it being needlessly annoying and using a different form than it's source material, it technically also changes the mechanic:
D20 + modifier vs. DC is "open-ended", you roll your dice and add your number to it. It could theoretically go to +1.000.000 if that was the scope of the game.
D20 vs DC - modifier is "closed off", in the sense that you can never, ever roll higher than 20 on a skill check since the modifier is added to the DC instead, and DCs can presumably go no lower than 1.
It seems like a unneeded change that has the potential to actually complicate things down the line as well.
Probably the reason why there is no expertise in this game.
