Preventing high rep users from answering _good_ questions from low rep users means Jon Skeet and Eric Lippert won't see them and be able to give their often spectacular answers. You're suggesting cheating low rep users who do a good job of reading the help documentation first from getting the best possible answer... and encouraging people who ask and answer poorly to continue doing so.
How many more answers to How do I fix a null pointer exception in Java ( http://stackoverflow.com/questions/linked/218384?lq=1 ) do you want to have on the site?