When X-T1 was first released, there's been a lot of whining about its locking ISO dial. My problem with this dial is totally opposite: I would like that damn button to lock not just ISO, but a drive mode dial as well. It gets knocked off way too often.
As a matter of fact, I won't mind if the X-T1 successor had a similar locking mechanism on a shutter speed/metering dial as well. The only dial on a top panel that should always remain unlocked is a compensation dial.