Why would someone want to use Pot of Desires, other than to draw 2 cards?
Why would someone do this? Is gaining 2 cards worth it?


Exactly.

Banishing 10 cards face down is the trade-off for drawing 2 cards; it's up to you (or the deck builder) to determine if this trade-off is worth it.

Having a card that just lets you draw 2 cards would be too broken. Such effect should have a trade-off to make it more balanced, and that is why this card requires banishing 10 cards.

In theory, no one wants to banish 10 cards facedown, because as they are facedown you can't recover them by any means (at least as far as I  know, as you don't know what card it is).

However, in practice, drawing 2 cards may be worth it, and even decisive for the game result.