Everybody is active. Now the point is everyone intersecting in a communal flow. The energy level and physical demands have risen. Modern flow dances are learned for the moment and forgotten. Everyone being active also eliminates 1's-only figures and triple minors.
Sicilian circles are often impossible.
More emphasis on aerobics and less on moving with the music. Bob Dalsemer points out that today's dancer has been staring at a computer screen all day and wants to MOVE and be social, whereas 20 years ago, folkies who loved folk music wanted to learn to dance to it. So dancers pay less attention to music and more to moving. For aerobic dancers, getting in an extra twirl is more fun than starting the next figure exactly on the beat. Despite the proliferation of types of music and the wonderful bands out there, dancers do not seem to adjust their dancing styles to the mood or type of music, even though they clearly are energized by good music.