Well the fact is that in the thread you started to discuss prophecies supposedly fulfilled by Jesus there was not one you were prepared to argue as a definite example of a significant fulfilled prophecy, might have something to do with it.
The fact that there are genuine messianic prophecies that still remain unfulfilled is also relevant. (Christians say that they will be fulfilled at the Second Coming, but why should Jews believe that ?)
It really isn't true to say that Jesus was so obviously the Messiah that the Jews should have converted. Accept that and it is no harder to explain than the question of why all Christians are not Mormons or Moonies.