I'm really wondering here. If you want people to actually like the game your forcing them to watch an advert on, is it really in your best interest to make the x as small as you possibly can? and likewise, do you need to force us to click said x multiple times? do you honestly think that this is how you get people to install and try games, or are the advert companies just using this to lie about the clickthrough rates?
I would prefer to believe it's the latter, but it may also be a design choice that merely reflects a general disdain for the user, rather than being motivated by actual greed or cynicism