Ramped or not to ramp that is the question

Are there any reasons to go one way or the other? Ramped barrels require the frame to be machined but is the juice worth the squeeze? The custom guns i have seen are all non ramped. Why?

Simply not needed with the 45 case..on higher pressure rounds 9mm, 38 super, 10mm the case needs more support thus the ramped barrels, which cover more of the case near the ramp..