Scoring was fixed in SL.
Making “smart score” for m+ would be almost guaranteed to be unjust. It would also mean another balancing nightmare to blizzard and they are not stellar with just the classes, trinkets and the content either.
This is not a problem. There are ppl who find no issue with timing 10s on the first week in 636 and then there are ppl who find it challenging even in ~665 full hero track gear.
Premade works fine the way it is.
It is to prevent farming priory and rookery for weekly.
But I think it would be better if every key would always offer two options. Always 2 random dungeon.
So a key which works in workshop would be usable in cinder as well.