Sure, you feel hot air but you lose the proper air flow and pressure needed to cool everything.
The front of the hood has a seal across it. The piece above the battery has a seal on top which completes the seal next to it along the rear of the hood on the other side. Air is brought in through the front and routed down and out along the drive train tunnel and out the rear. If you put holes in the hood you lose proper air flow to cool everything. Holes are just for style.