Yes they do matter.
I've written quite a few in the past month and a half. That is written letters with an envelope and a stamp, to elected officials both pro and anti gun; to companies who are located here in NY; to companies who may do business with NY State and municipalities.
Most but not all of those letters have generated a response in the form of a reply letter and in the case of some local and State politicians, a phone call. Everyone appreciates a well thought out and written statement or question. As expected, some respondents did not see things as I did. of those who didn't, most still appreciated the point of view. And I would like to think I had a hand in changing the opinion of one official who was somewhat anti in the beginning and lately is speaking more Pro.
Yes they do matter.
If someone has an interest in your opinion or your wallet, they need to receive a letter letting them know how you feel about recent events and pending legislation. Be strong yet polite in your wording. let them know you are un-bending in your opinion. Make sure they know your future choices depend on their choises, decisions, and or votes. Make sure your contact info is complete in that letter and it is neat and clean when you send it. (I went to a parochial school and this was literally beaten into me)
Our ability to exercise our 2A rights depend on both your letter and mine.
Pete