Incidentally, it's been pretty well documented that GR didn't just experiment with illegal drugs. He started smoking pot seriously during STAR TREK's third season if not sooner, and later got addicted to cocaine. Can't say I admire that behavior.
Not refuting it, but could you tell me where that information comes from? It wouldn't surprise me that he got into drugs along with the whole sweep of the counter-culture movement, and I read that he married Majel Barrett in a Buddhist-Shinto ceremony while kind of implies him getting into eastern ideas ala the Beatles, but this is the first I've heard of him being addicted to coke.
Of course, I didn't know about Nimoy's bout with alcoholism until fairly recently.
There aren't too many family people who are going to sign up to not see their spouses and off-spring for a full decade. If they had held to the original concept, there'd be no way to do it without families aboard.
I don't think that changes things. Dragging your family out into uncharted space seems like a reckless thing to do. Kind of the intergalactic equivalent of the Mosquito Coast. The only way to white-wash that is to just not put the ship in much danger of being destroyed, which is basically how most of TNG went down.
People kind of munge TNG in with TOS now but there definitely was a concerted effort to show how technology had improved since the days of TOS. And the more you allow technology to progress like this, the more you remove some of the adventure aspects of explorers being out there in the middle of nowhere roughing-it. Letting the Federation and Klingons kiss and makeup didn't help matters either. There's a line to be draw with utopian ideals and if you go too far, you remove too much suspense and conflict.