Maybe things have changed since I took my tests in '98, but when I see "ASE Certified", all I see is a sign that a person is proficient in taking standardized tests.
In 98, I was in the industry for 11 years already, as a mechanic for 6 of those. I was a tech at a VW/Audi/Porsche store, and they offered to pay for our testing. I took 4 one night, remaining 4 the next night, passed them all without looking at a practice test beforehand, and *boom*, I'm now an ASE Master. Still the same green noobie tech that I was 2 days prior.
Like I said, maybe things have changed since then, but I got zero real value out of it, other than being more hireable.