You catch more flies with honey

When thinking about what to write about this I turned to Google and found some interesting responses. nevertheless roughly translated it means that you are more likely to get what you want from the people you want it from if you are nice to them and pleasant in the way you deal with them.
It seems adversity brings about the best in some people and the worst in others. The current DPTI project has reaffirmed this to me many times over. Those residents with genuine concerns that have approached me either by email or in person have more often than not been extremely pleasant in asking for my support. This support has been given willingly and in return pleasantly. These people have achieved much by being pleasant and polite at all times.
Others choose to criticize constantly not what I do but who I am. And yet they still expect to be treated in the same pleasant and polite way that I treat other people and still expect that I will work with them to achieve what they want. When the success is achieved it seems they usually achieved it on their own!
What I also don't understand is why people think it is OK to put something in an email that they would never say to your face. So does email give people a license to be rude?