A little while back, in response to a critical hit rolling snake eyes, my group adopted a house rule as follows:
Instead of rolling dice for damage twice, roll them only once and add the maximum result possible from those dice, example on a critical hit: a d8+2 attack, does 8 + 2 + the result of rolling one eight sided die. This assures that critical hits are impactful, always resulting in more damage than is typically possible. Note: As per RAW, spells that roll a d20 to hit, can critically hit. (Added 11/6/19)
Some things about that rule change are in my mind excellent. It eliminates the snake eye critical, or more generally all critically that hit for less than a good normal hit. It also speeds things up by eliminating the need to make extra rolls or borrow dice (though that can be fun too).