Hi Tufty, and welcome to the forums.
From reading your extensive cases for and against, I was in a very similar position as you. Certainly people were very surprised when I decided to quit 5 months ago.
So why did I do it? I was just plain tired of it. Tired of obsessing about alcohol. Tired of counting units, trying to keep under weekly levels I'd set myself, tired of thinking about whose round was next before I'd even started the pint already in front of me. Tired of worrying about what hideously embarrassing things I might say or do if I slipped up and had too much. Tired of being reminded of those things from the last time I slipped up. Tired of hangovers, of going into work but not getting much done. After a very intense 35 year relationship with alcohol, I just decided I'd had enough.
And the bottom line is, I don't regret quitting at all. Life is much, much better sober. I still meet friends at the pub, laugh, joke, enjoy good banter. I still go to gigs and have even more fun because I can stand at the front of the stage for hours without constantly needing the loo due to 6 pints of bitter sloshing about inside me (too much information?). I like waking up without hangovers. My relationship with my kids is even better now.
As others have said, you need to really want to stop, and maybe you haven't mentally reached that point yet. But it might be worth asking yourself what would need to happen for you to reach that point. Keep in mind that nobody's life was ever destroyed by sobriety. Alcohol, on the other hand...