It is a proper mental leap to make, and it'd be wrong to play that down, just like there's no point in denying the simple facts that (for most people anyway) alcohol is A Nice Thing and social drinking is fun. The mere act of being on the wagon doesn't stop that from being true, and not being willing or able to embrace the abstinence option (yet) isn't something to self-flagellate over - none of us have any control over the way we're wired, after all, we just have to deal with it.
For me at least, every time I tried to kick the habit myself or own up to it to others, this big "OMG YOU'LL NEVER BE ALLOWED TO DRINK AGAIN"-shaped monster kept looming and that wasn't something I was prepared to fight with at the time. Partly from a fear of missing out on the pub culture/social drinking thing - which, of course, has proved to be absolutely fine*, even if I'll probably become a diabetic from all the sugary drinks I'm consuming - and partly the aforementioned English embarrassment of not wanting to make a fuss about something that you feel you "ought to" be able to control, e.g. (in my case) "secret" drinking. And if your alcohol consumption is excessive from a medical advice point of view but it isn't having a practical impact on the cornerstones of your life yet - your ability to work, your relationships, your ability to look after yourself, whatever - then you tend to think you're doing fine with it.
If you really do want to make a change, it might be the case that circumstances collide and something happens to flick the switch - that's what happened with me - or you might just get to that point gradually, as it sounds like you've been doing for a while now anyway. As you say, blood tests and the like are often the real eye-opener. My liver function's only started properly deteriorating in the last year or two, and of course I'd been deflecting the questions at the doctor's every time - why no, I'm not consuming any more alcohol than usual, I wonder what the problem could possibly be? All I can say is, if nothing else, it's a relief to have the simple facts on my medical record and to be able to actually talk about it with people, and you might find that too. Or you might not!
That all being said, I have no intention of becoming an evangelist for sobriety - I think booze is brilliant, I'm just not allowed it myself right now, but that isn't going to stop me from buying my dad an indulgently expensive bottle of whisky for his birthday or getting the beers in on a night out. Except when the Fish takes us to some wanky place in Clapham where they "appreciate his presence at the bar", in which case he's on his own.
* it helps, of course, that none of my good friends are of the 'normal blokes drink, non drinkers are a bit odd' breed described by the esteemed poster above
Plain ones are pretty bad.