Perhaps the problem of tissue rejection can be controlled, as with current transplant recipients, but there are many failures, and suppression of the immune system using drugs is a serious problem in itself.
So research with these few cell lines is appropriate, to learn about the nature of the tissue differentation processes. But to find therapies and treatments that will actually cure anyone, we ought to be looking where the real answers are likely to be found. And that will probably start in the patient's own body, with his own, more mature, somatic stem cells.
We will learn to reverse spinal chord injury paralysis et al. similarly through unimpeded research.
Drug suppression of the immune system is definitely a serious problem. Study and research may well provide more satisfactory solutions.
Evaluation of mature somatic stem-cells may yield results, but it may not. Bush's policy toward this enormously important research is far too restrictive (and this from one of Bush's strongest supporters).