Lap me gently...

[S0ULphIRE]

Some block are flat, some are made so there's extra pressure over the middle of the cpu.
I dunno, there's probably really not gonna be any need to lap it anyway. I'm pwning you guys's little benchmarks already with air cooling

 

[C0RR0SIVE]

It's not just for flatness, it is also to help remove any micro cracks/crevices that are present ya know -.-

 

[Luke]

^The real only reason is to get it flat for better heat dissipation over a flatter service, or to get it down to a metal that is better at conducting heat.