A couple versions ago there was a feature that I really enjoyed but is no longer in the game. I hope I can describe it well enough.
Lets say I have Muldrotha the Gravetide in play and its ability lets me pick a card from my graveyard. The feature I am thinking of would allow me to tap on the mini-card preview to fully display them. This feature is not limited to Muldrotha: its any time you have to pick a card from other zones. Unless you know every card in the game by heart, its absolutely vital to making informed decisions.
I would really like this feature to come back!