I think that by allowing federal funding of stem cell research, we can understand things about the cell that would not be possible before. You have to think of it as baby steps. That's what most science research is. Sure, you hear the news talk about this new cancer drug that was developed. But, what they don't say is "This drug was based on 15 years of basic science research done by over 50 labs throughout the world." The same will go for stem cell research. Yes, eventually, we may be able to replace pancreatic cells that don't respond to insulin in diabetics. More importantly, though, is that we will understand what exactly is going on with the cellular pathway that causes it.
In my last lab, we published a paper about how BRCA1 (the "breast cancer gene") is involved in one step of DNA repair. It's a small step and not as ground shaking as curing cancer. However, based on that small step, researchers can eventually develop a drug that would specifically target that process after a BRCA1 mutation and possibly give life to percentage of breast cancer sufferers.
So, yes, embryonic stem cell research should be federally funded.