If you were playing with a physical deck of cards, it'd be necessary, as in Poker, to shuffle the deck and deal out your hand. The same would be true for your opponent. Thus, there'd be an element of randomness in those types of games - just as there is in Poker. If all players could simply select their best hand/cards all the time, that'd be no fun whatsoever. The whole point of having a minimum amount of cards, with different levels of power, is to ensure that hands are varied and not necessarily always with the best cards you have.
I've seen people complain that gold cards are too common, and the silver should return (I agree); however, in a deck of of cards with minimum 25 cards, it's pretty obvious that gold cards being played should actually be rarer than having to play a bronze card. Likewise, in card games such as Poker it's not always the case that you'll be dealt an ACE - sometimes you gotta make do with a deuce (2).