The core of the Word of Wisdom, according to the revelation itself, is the avoidance of addiction peddlers. D&C 89:4 makes this clear - and D&C 89:3 is probably the most overlooked, profound verse in the entire D&C. It says that the Word of Wisdom is NOT the ideal "law" - that, rather, it is "adapted to the capacity of the weak and the weakest of all saints, who are or can be called saints."
When people claim that the Word of Wisdom cannot be revelation from God because it prohibits substances that are good for us when used in moderation, I always point out that such information is irrelevant to the actual wording of the Word of Wisdom itself. What is best for most is NOT the standard articulated in the revelation; what needs to be followed by the "weakest of all saints who are or can be called saints" is the standard. What does this mean?
There are saints who cannot handle any consumption of alcohol or use of tobacco (or other drugs) without becoming addicted. There are "conspiring men" who recognize this and spend millions of dollars trying to get these people hooked. Furthermore, there often is no way to know where your individual limit is until you cross it, and sometimes that simply is too late once you've crossed your own "addiction line". I know way too many people who think they are social drinkers but have moved past that quite clearly, and I know way too many people who got hooked on cigarettes or chewing tobacco after their very first use.
One more point - and this one is something that almost never gets discussed:
If you really are strong enough not to get hooked, you are strong enough to choose not to partake. If someone can't give up alcohol or tobacco or coffee - if he has to justify continued use by citing physical health generalities, there might be more "addiction" going on than he realizes - meaning he might not be as strong as he thinks.
I agree that the rest of the Word of Wisdom probably is a general health standard influenced by the understanding of the time, but the part that has survived in our modern emphasis is the "eternal" aspect - the avoidance of addictions that subject our will to "conspiring men" and weaken our ability to give our will to God. If God explicitly says, "This is not the ideal, but it's what I want my saints to live" - and if it initially wasn't enforced as a commandment (as stated in the revelation) but was changed later (I think) because the influence of those "conspiring men" grew and those in the Church had time to adjust to it - and if it now is a requirement for temple attendance (I think) because "conspiring men" are finding more and more and more ways to addict people and influence their acts and decisions - I can understand and accept that without any difficulty.
Fwiw, as someone who has come to realize he is prone to a bit of obsession and "addiction", I appreciate being raised with the Word of Wisdom and never having to go through the Hell of ditching an addiction. I appreciate being able to take hundreds of dollars a month that some of my friends spend on alcohol and tobacco (enriching already rich, conspiring men) and, instead, spend it on good things of my own choosing - like charitable causes and avoidance of consumer debt (another addiction of conspiring men - interesting how one feeds the other). I appreciate growing up in a culture that did not glamorize alcohol and tobacco use, keeping that type of temptation away from me in my most impressionable years.
I've seen the impact conspiring men have had on our society. It is enormous and absolutely appalling. I will NEVER criticize the Word of Wisdom, even if it does include outdated health statements - especially since the Church no longer stresses, emphasizes or even teaches them actively. For me, that's just another indication that our leaders are inspired to emphasize what still is relevant for our day and move beyond what is not.