Why do GPU's only take in air from the top of the card?

So I have a GTX285 and a tesla C1060 in my box, the only way to mount them was right on top of one-another.
The problem is that the main air flow is through the top of the card.

Is there any reason why its not through the side??
Most of the time my cards dont run too hot, gtx285 @70-72C and the tesla @60-61C

But when i actually start doing more processing, taking longer than a second or so, the gtx285 jumps to 84C, where as the tela only goes to 70.
This i assume is because the gtx 285 is getting limited airflow due to the tesla blocking much of it and the proximity of the tesla causes it to suck in warm/hot air.

I dont mean to be rageing about something i cant change, but am i the only one that sees this flaw?

Most of the intake is from the side of the card facing the front of the case, not where the fan is.