To OP's original question - things changed for sure - off at 60MPH is most likely to be stopped by grass/gravel trap. Off at 100MPH is many times more likely to cause a roll or put you into the wall. Higher speeds and heavier cars with the same run offs increase the cost of mistakes, so nannies are more important.
I never use the normal (non-MDM) mode on the track because it's blocks any rotation completely and thus changes driving feel too much. I once had it on thinking I was in MDM and almost had an off because adding throttle to push the car around the bend just did nothing.
But MDM has it's uses, I think - for example, I use it when learning a new track to make sure I have safety net if a turn "surprises" me. I know ideally that should not happen, but sometimes it does on a new track. Another time when I use it is when experimenting with the line or moving braking points - sometimes such experiments may cause "oh-shit" moments, so trying the experimental approach with MDM is a good safety net - important for a really fast car without racing-grade safety equipment. I wish there was a more track-friendly mode, like Corvettes have - something that let's you slide as much as you need and intervenes only during inevitable spin.