This severely nerfs the Rogue class. The difference between expertise and proficiency in tier 2 goes from +3 to +1.
If it were up to me, I would rewrite most of the numbers that 5E currently uses, but that would require a new edition.
The difference from a 1d4 (2.5 average) and a 1d6 (3.5 average) is +1, so the rogue still ends up with a boosted chance of success. Also, the rogue gets a chance at a higher possible maximum.
All of that is on top of sneak attack and the variety of other things the class gets as a whole.