Yes, asses look extremely nice and they're extremely nice to grab. They look amazing when you do it from behind (I'm trying to not get NSFW banned again bear with the toddler language) and shit. I love ass myself.
But god damn, boobs look amazing as well. And there is cleavage, underboob, sideboob, all the boobs angles you can see. But you won't see ass cleavage, sideass or underass (unless she's wearing a mini short).
Also I'd argue you can play more with boobs. Because what do the boobs have that asses don't ? That's right, nipples.
I was not expecting such a crushing defeat, I may be asking the wrong population.
Whilst I agree with that opinion, I believe it's much more frequent to have a flat chested girl than a flat ass. I've seen many girls with barely any chest but almost all girls I see have an ass, some may not be the greatest, but they're still not almost flat. Even boys have fatter asses. Because we use our asses to sit on stuff.
Therefore it's a false equivalence to base the boobs-ass debate on that statement you made, as in a real world scenario you don't often get a flat-ass girl who doesn't also have flat chest.