The site (for now) caters too much to those who already have a set routine. I would develop standard plans that users can pivot from. (Those standard plans should based at minimum on gender, weight, and current fitness to be usable.)

Personally, I would love to use something like this since I find myself floundering at the gym and picking random exercises when I am not on the treadmill. But as a woman, I don't want a suggested routine of 100 x 50 lb bicep curls.