- I think it's unconstitutional.
- It would cause more harm than good (and the good would be questionable - I mean, I don't consider making guns harder to get a good thing).
Edit: To expand on B, IMO gun control mostly if not only causes issues for people who want a gun for personal defense or recreational purposes. Limiting those in any way (especially the personal defense aspect) is bad in my book.
Edit 2: tl;dr - because it won't work.