Since the current Mulligan rule is easy and quite close to the official ruling, it is probaply the best to keep it, but since the Scry-Mulligan was introduced there was one thing I did not like:
The Scry helps to close the gap between having 7 good cards and taking a mulligan to 6 cards. That works pretty well and it feels not that bad anymore to go to 6 cards. But then if you have to go to 5 cards, the gap becomes bigger since you get no further advantage to compensate the card disadvantage.
Why not give a player that goes to 5 cards the ability to Scry 2? And if you go down to 4 cards, you could Scry 3, and so on.
I do not want to say we should change the rules (well maybe), because staying close to the original rules is always a factor, but what do you think of that?
It makes sense to me, too. But I think the factor of staying as true to conventional Magic rules outweighs the (slight) gameplay benefit which might be achieved with your proposed rules change.
I would rather opt for a total return to the core and just go with the normal mulligan (abandoning the free mulligan altogether).
I agree with Maqi.
We should consider to dismiss the free mulligan and go back to the official mulligan rules.