Sorry - I completely disagree...
I suppose that they have an advantage for one who doesn't like games, but all they did was sit around. I was very dissapointed with them - I got a connection and loved it, and then read about some of the older ones. I finally read about "Angel" and decided that I wanted it more than anything else in the world. I searched and searched - finally I got it, and it did NOTHING! They just gave everything new names! Boring!
The ocean does sort of sound cool because it's supposed to be harder, but the old ones seriously just sit around, and take FOREVER to evolve. My favorite part of Tamagotchis is trying to get the good characters and mating and stuff, but the old ones grew up and then just sat around until they died with no cool animations or anything, and you had to wait for the life cycle to restart. There weren't even very many characters! Old Tamagotchis were, in a word, pointless.
(This doesn't apply to Morino or Ocean - I never tried them. However, the Morino cocoon stage still sounds really boring.)
(I also REALLY want a Mesu and an Osu. Not sure if those count as "old ones".)