Why bother trying?
Has animal research been able to validate any therapies involving (animal) embryonic stem cells? If not, what is the purpose of experiments with human embryonic stem cells? Unless one wishes to subject adult human subjects to completely non-validated experimental therapies, I see no possible benefit to performing experiments with human stem cells before ESC therapies are developed that work on animals. Are there benefits I'm not seeing?
Also, suppose that all of the embryonic experiments go as well as you could possibly imagine. What practical applications do you see? It seems to me that even if an ESC-based therapy is found that "works", using it would require finding a compatible ESC donor couple, harvesting some sperm (easy) and an egg (not so easy), fertilizing the egg, harvesting the stem cells, coaxing them to do what's needed, and hoping they don't get rejected by the recipient. Somehow that seems more difficult than just taking some cells out of body fat which likely won't need as much "coaxing" and which won't be rejected.
Do you see any way in which ESC's would be more practical?