I have been writing letters to editors since at least 1986. Over 100 have been sent, mostly since I got e-mail in 1999.
Generally I write on 'domestic' issues to the local paper or The West Australian. A few letters go to engineering or car magazines.
The only point in sending most letters is to get them published, and therefore get your message across to readers. My success rate is moderate.
Reading or writing Letters is a subculture in which few participate. One reader actually said in his letter "I should get a life". I pointed out he himself was in this subculture!
I wrote one back in 1972 to the "Evening News" regarding Palestine following an annoying editorial. The paper then published an answer from a Rabbi putting his biased view. I suspect a deliberate trap from that paper, but the anti Palestine editorials did seem to stop.
For more information re Palestine see my letter to the Wanneroo Times.
A further objective is to educate editors on technical matters. A minor achievement was to reduce the number of times they print "kilowatts of power". More