This is woefully incorrect. People love GOOD shows... the parks just haven't added them as much recently.Good ones are.
Granted, American audiences seem to prefer rides over shows, unlike European and Asian theme parks, some of which are entirely show centric, like (Ben still my beating heart) Puy de Fou.
At Disney, the Festival of the Lion King is insanely popular with shows every hour filling to capacity (enough to handle 1,200-1,400 each show. Guests are getting in line 90+ minutes prior to Fantasmic, which holds about 7K guests and fills the theater to capacity each night.
At Universal, Bourne is insanely popular, same with Grinchmas during the Holiday season. WaterWorld at USH is a must-do.
Great shows will always be just as popular as any theme park ride. The parks just haven't invested in them as much.