Probably not, since diversity of Psychics increased immensely and Dark-and-Steel types were introduced. Half Hypno's utility comes in having Psychic resistance, being one of seven fully-evolved non-Legendary Pokemon with Psychic typing, and one that you get EARLY. If you have Darks or Steels? Meh. Keep on bench.

Exeggcutor is better in every way, but you get it much later. Hypno at least comes in early enough that you can start using it to Headbutt its way through Gary's Kadabra. (And, if you don't have a Kadabra of your own, it makes a good Psychic-type as well.)