The second issue relates to the unknown. Even after the map is completed, we still won't know the function of each gene. In other words, what we will have is a very detailed road map. We still need a car filled with fuel and armed with a good navigation system to get us from one point to another. Moreover, the potential applications are still all unproved.
Mapping is only the first step in a long process.
The road from gene identification to effective treatment is long and fraught with challenges.