M-4 ramping serves a purpose, and that is to allow non-standard Ball type rounds from being feed into receiver lower flat just before the standard ramps.
Note: Fact is that a lot of sellers really don't want to "lead on “ is the fact that only Colt offers the M-4 ramps from the factory. If you want the M-4 ramps, then you will need to buy a Colt M-4 upper and barrel. If you want the ramps added to a Non-Colt upper/barrel, then you would need to either add them yourself, or send the upper/barrel off to have them milled. To worry about something so mundane as a little aluminum expose at the front of the receiver, when the carrier is exposing other parts of the upper receivers aluminum by scrapping the anodizing off, is just a little deep to try to wade threw.
Trust me, I have a tendency to load some pretty weird loads, and the M-4 ramps are the difference between them feeding or not. To dismiss them as just a fancy is just way over the top.