i guess we all have different levels of attention-to-detail and expectations.
i expect the buttons on my old chevy malibu that i bought (used) for $12k to look new forever, if i don't abuse them. On my benz, i expect the buttons to look perfect, unless i do something to drastically harm them, accidental or otherwise.
It all comes down to "attention to detail". If a manufacturer doesn't put the proper effort and care, or doesn't have the capacity/capability, or doesn't have the knowledge of dying buttons properly enough so that they look brand new after moderate use, then where else might they skimp out? To me, it's the little stuff that really tells the story of what goes on behind a car, the big stuff is obvious, and well laid out (and marketable, etc., as a brand can't tout "we make buttons to last a lifetime", but they can "we handle great and are fast", so it goes a long way when a company goes the extra mile on non-marketable areas).
When i was looking at (used) cls's before my (new) e-class, i couldn't find examples without the soft leather door armrests all scuffed up, or without the plasti-chrome trim around the cup-holder peeling, i didn't care how much hp and leather/suede that cls55 had, i kept thinking "pos" when thinking back to the interior wear-strength.