I went to memory alpha and read some of the writers quotes. It appears that the writer got what he wanted in the fans reaction.It is also interesting that the original ending had Tuvix sacrifice himself.
"Ken Biller then took over responsibility for the episode. "I ended up taking it over and completely rewriting it,
" he said. "It was [a] tricky episode, because it could devolve into something farcical. It is another one of those semi-hokey sci-fi premises, sort of the opposite of what I got in 'Faces' [....] We wanted to do something a little more serious and philosophical [than the original plot] and it began to emerge as we talked about it that there was something interesting there once you got past the hokiness of the set up. It started out as a joke. What do you call the guy? Neelok? Tuvix? It almost felt like a '60s sit-com. Brannon [Braga] and I even [came] up with a little theme song. So the trick was to see if we could actually make something compelling out of it.
" Thus, the writers experimented with the notion of making Tuvix greater than either Tuvok or Neelix alone and asked themselves what would happen if the Voyager
crew found a way to return Tuvix's two constituent parts. (Cinefantastique
, Vol. 28, No. 4/5)
Initially, the episode would have ended with Tuvix realizing, through some event or the reaction of the crew, that, for the greater good, he had to submit to the procedure of being split apart. "For a while that was the idea,
" recalled Ken Biller, "But then we began to talk about it and consider what if he really wanted to survive and he doesn't want to die and be killed. Michael [Piller] posed that question to me so I give Michael a lot of credit.
, Vol. 28, No. 4/5)
Ken Biller then aimed to dramatize Janeway's dilemma at the episode's climax as much as he could. He explained, "I hoped to create tension at the end where it would be difficult for anyone watching to know what the right thing to do was [....] I wanted to keep asking the audience, just keep poking at the audience. There isn't an answer [....] It was an opportunity to show [Janeway] making the really tough decisions which captains are faced with.
, Vol. 28, No. 4/5)"