Bigger risk for the bigger reward for the user....a risk many finasteride users will not even take. And for the company, probably not worth the money it would take to go through the trials and stuff for a very limited customer base.
Let's be honest though- for most people it's easy enough to obtain dutasteride without a prescription.
You d*ckwads, there are so many studies done comparing the two drugs, and dutasteride had pretty much the same safety profile as finasteride. Only a slight increased risk in getting side effects, but still very very very low. Do some research. Sweeping out.