As someone who saw TOS first run (I was 6); and grew up with it in syndication, my reply:
1) TNG and the 24th century era Star Trek was too reconned from the original series; and the creative staff for that era ran out of steam. I also think that TNG era Star Trek was missing MANY elements that made the original series so good.
2) The original TOS actors were just too old to continue; and there was in fact A LOT of baggage with Trek's 'Prime Universe.'
Thus, I had no issues with and was happy to embrace a reboot with Kirk, Spock, and McCoy (and the original Star trek era) effectively revitalized.