So I've been pondering this for weeks. I tried watching and rewatching Wrath of Khan and Space Seed, and I just couldn't get in to them like I used to. I know a majority of people inside and outside the fandom consider TWOK to be the best Star Trek movie of the 11 but is it really? While I do enjoy it I can't help but feel that it may be oversold on it's amazingness.
This may be unrelated but part of it stems from Search For Spock, Everything TWOK set up is ripped away in TSFS. Kirk's mid-life crisis, career as an admiral, Kirk finds his son and loses him just as fast, Spock dies but is revived just as fast as Kirk's son was introduced and killed off. By Voyage home the only thing that remains is the Genesis Torpedo.