I was there, about 14 years old at the time and an avid fan having started watching the show in the early 1970s in syndication.
You have to remember that we had been steeped on endless re-watching of 79 episodes that we knew in and out, back to front. When TMP came along, we were all greatly excited to finally see new Trek beyond those 79 episodes – while it was enjoyable, some people found TMP somewhat disconnected from the series (less action, no colorful uniforms, etc.). So my distinct personal recollection is being really excited when I heard they were bringing Khan back, because it was a direct tie back into those 79 episodes we had been marinating in for the past 10 years or more, and promised some sort of return to the feel of those episodes.
M