What distinguishes integrating tipping and current system? If someone found your post useful he can send BTC to your own address in the signature (or profile) or even ask PM your address if you do not specify your address.
Ease of use. See my response before about sending carrier pigeons vs email, iphones etc...
The two main arguments against it seem to contradict one another.
1st argument - there's already a way to tip now, everything works fine so why improve?
2nd argument - there are no beggers/spam now because no one is tipping (thus beggers don't bother). Once you make it easy and people will actually start tipping it will open a pandora's box for all the evils that come with tipping