Actually, if you look in the DMG, the basic guidelines for DCs put you in the 10-15-20 range with some up and down based on factors that are very similar to what he just described.That's a bit of a circular argument, though, isn't it? Your DCs are high because the PC gets such a large bonus to the roll. If the PC doesn't get that large bonus you don't make the DC so high. A DC 27 lock is an automatic success for a high-level rogue with Dex 20 thanks to Reliable Talent.
That's a more telling argument, though I have plans for Sharpshooter.![]()
What he described was a pretty std st of DCs just like the same can be expected for AC.
But let's ask you the same question, if you the GM will just lower dnd raise the DC why bother changing the rules on expertise from +2-6 to flat +2? Why change z rule for what you already nerf?