As for the non-nuclear WWIII, I don't buy it either.
First it seems to me that unless Clancy weaseled some rationale to sidestep the nuclear issue, the story wouldn't have been very interesting. The conflict begins, and at some point, either side lose its nerves and used a nuclear weapon, and then both sides initiate extensive strategic strikes against each other. End of story. Would you buy a book like that ? I don't think I would - I don't care if the good guys win or lose, but I don't want to be cheated of a story because the world is reduced into a radioactive piece of rubble.
Second, I thought the Warsaw Pact battle plans that were published in the early 1990s showed that they planned to use tactical nukes from the get-go, to open breaches into the NATO lines immediately.
Still, Red Storm Rising remains one of the best WW3 books ever published. I read General Hackett's book and found it a tad boring, if certainly more objective than RSR. I also read Eric L. Harris "13th july 1999" (IIRC), which utterly bored me, and Ralph Peters' "the War in 2020" was almost put me to sleep. I much preferred "Red Tiger" by Harold Coyle (not 100% sure of the title here, a story about a US tank outfit in WW3).