You have a point. Your writing of a book on subway trains was a magnificent achievement. And, yes, some of the responses posted to your opinion about the El were personal and vitriolic in nature and not reasoned responses.
But opposition to the taking down of the Astoria El is based on solid reasoning. I personally would favor the El's replacement by a new subway line, hopefully also extended to the Bronx or the airport or East Elmhurst, which needs and wants subway service. This way, train service is maintained but the El structure goes away. However, the dismantling of an elevated line and its replacement by buses has occurred in the Bronx and in Manhattan - and years later all of us have come to regret it. It's important not to repeat mistakes like that.
In the meantime, if it's important to you, write to MTA advocating for better El maintenance.