Purpose of overheads?

[Bezo]

I've noticed many members stressing the importance of overheads. Some have even said they're the key to a good sounding kit.

Right now I'm a one man band playing guitar, bass and keys. Without the space or skill to record a real drum kit, I've been programming them with pretty good results. I record hip hop, r&b, funk and rock. And with the hip hop tracks, I aim for a more organic sound than most, so it's imperative that my drums sound as real as possible.

I'm familiar with, and getting better at humanizing the programmed drums via timing, velocity, ect. My question is, what's the purpose of the overhead miking on a kit? Would it be worth trying to duplicate that? If so, do you have any suggestions?

To let you know how I currently treat my drums, I NY Compress them 95% of the time. Small or Medium Hall reverb on the snare, toms, hi hats and cymbals. Ocassionally, some white noise added to the snare, and/or sine to the kick via aux sends.