I think the 1 on 1 better "proves" your skill over a given opponent for the most part. Especially because you can control many of the variables that occur in the MA, and rule those out. Of course, everyone has "hot" and "off" days.
I've just never found those 1 on 1 duel-type fights to be very interesting or stimulating. I'm bored in the DA by the time the game loads and I can see who's on the roster. Win or lose, ho-hum, I'm not all that interested...
Multi-kill hops in the MA require a different set of skills, and for me are infinitely more stimulating and interesting, and make me try harder to beat my opponent and land some kills. Having ten kills in my pocket makes me try harder to not die than having 1 or none does. I consider my "life" more "valuable" when I have kills to land. That doesn't make me timid, since I'm also greedy (landing 11-12 is better than 10!) and conceited (LOL, no way will that high spit get me! I'm MtnMan! Come 'ere you dirty varmint! Lemme take your pelt!).
I've always seen duels as "warm-up" for the "real event" (MA), and as such I don't care much about victory/defeat in the DA. But, again, even though I don't find duels exciting, I do think they "prove" skill over a select opponent in a way you can't often replicate in the MA.
I need the constantly varying engagements of the MA to keep me interested. Is my next fight going to be "fair", advantaged, disadvantaged, against a slower or faster plane, better turner, worse turner 1 v 1, or 1 v many? Who knows! Just wondering makes me want to log on!