Status does a great job motivating customers who buy coach, or at least fly coach a substantial portion of the time – for instance the road warrior whose company will spring for business class internationally once or twice a year but has a rule of 6 hours or more for premium cabin so domestic trips are mostly out up front.
Status does almost nothing to motivate someone who buys all premium cabin tickets. When elite status spending requirements are so high they’re met primarily by people who buy first class, elite status is meaningless.