And since we've discovered that EVERY Soviet plan for an attack on NATO called for a massive nuclear attack,
Erm… that is incorrect. While there are many Soviet plans that called for massive nuclear attacks from the go, there were also many that were devoid of any nuclear use at all or had the use of nukes as optionals. Soviet nuclear doctrine until the late-80's focused on using nuclear weapons to safeguard their conventional superiority, so even many of the nuclear use plans usually envisioned as pre-empting or retaliating against NATO nuclear use.
All known Soviet warplans and exercises were setup with variations on two premises:
1. NATO managed to launch an assault with a reasonable element of surprise that establishes NATO conventional superiority and/or launched a nuclear first strike, so after NATO attack there is no other choice than to deploy nukes to break NATO momentum.
2. NATO preparations were discovered before they managed to commence with the attack, so a conventional assault is launched in a pre-emptive strike. Usage of nuclear weapons in that case depended on how the war further developed.
The nightmare scenario (for NATO) was that the Soviets would decide one day for some reason to launch an aggressive war, using one of the pre-emptive strike plans as a quick template. In other words, the fear was that of a sudden change in Soviet intentions, since Soviet capabilities supported a potential offensive war until the late-80s.
Following that was also the more reasonable and somewhat less implausible fear of the Soviets miscalculating during a crisis and ordering the implementation of a pre-emptive strike plan out of the mistaken belief that NATO was about to hit them first.