The idea sounds good, but there are 2 main objections as I see it.
1. It would require a major overhaul in the GUI. I'm referring to the initial display of 16 cards and a way of selecting cards and confirming your selections.
2. Matches would take longer because of the added step(s).
Zanzarino has continually emphasized simplicity and speed in his design, so I doubt something like this would ever be taken into consideration.
An alternative to this would be a card that creates similar mechanics, such as the Lucky Fox (
http://elementscommunity.org/forum/index.php/topic,12693.0.html) card idea. Choosing from a small set of cards requires less space and being part of the card's function it is still subjected to the normal rules and time length.