Might I say, you Dry January gang, don't jump ship! I look forward to watching your progress through the coming month and hope you get lots of support and a well-deserved sense of achievement from your challenge. 
As a moderate drinker, I am not participating as I find January bleak enough, especially when the Christmas lights go out, and would not want to depress myself by denying myself any of my pleasures.
I'll try to answer a couple of your questions, M0nica, from my perspective:
genuinely puzzled why people want to drink alcohol frequently and enough to feel a month without drinking is really difficult
I drink alcohol frequently (typically, over a week, a bottle of wine and a couple of G & Ts, ie around 12 units) because it's one of life's pleasures. I would not relish giving up altogether for a month, any more than I would want to give up fish, or bacon, or cheese, or chocolate, or my many daily cuppas.
I would be interested to hear from people who do drink more regularly why they enjoy the taste and effects alcohol has on them when they are so unpleasant
Unpleasant? Not to me, M0nica! Or to anyone else who appreciates a glass of decent wine or a cold G & T, a glass of craft beer or a good cognac, etc (sorry for putting those images in your mind, Dry January people
) As for unpleasant effects, that surely only applies to over-indulgence?
What amazes me is that so many regular drinkers, I do NOT mean problem drinkers, say how much better they feel, physically and mentally after doing a dry month, in which case why on earth do they drink in the first place or return to it afterwards?
Apparently people have the same feeling of well-being after a month of clean eating, or cutting out red meat or caffeine. It gives the body a break and boosts well-being. For most of us though, it's not something we want to stick to for the rest of our lives.
Hope this helps 
jingle, I love the taste of good red wine, and I'd rather have a glass of Merlot than a greasy doughnut any day
!