If you can perform non-optional actions on a card to the fullest, then you must do so. The clarification is only to alow you to play the card even if you DON'T have a second card in there (which wouldn't be possible, say, by MtG's rules). If you CAN find 2 cards, then you MUST find 2 cards.
As for not looking through your opponent's iscard piles, it's actually fairly simple: it's to reward the better player, the one who pays most attention, plans around, etc. So now, it's up to me to remember if, for example, between playing and discarding, your deck does not have a single
Hate in it anymore so I can exhaust my companions, I can't just pick up your discard pile and check.