I don't think character hatred is based entirely on threat to couples. There's that; it's reasonable to dislike a character whose presence threatens something you enjoy. Tess constantly interrupting Alex and Isabel really bugged me. Yes, Gazers wanted Alex back. The show had time travel. The show had far less interesting characters coming back from the dead without waiting their turn. There's nothing wrong with that either.
But it
is wrong to pretend that that was the whole story. We didn't think that the Interloper was right for Isabel. He didn't treat her right. He was too old. He didn't appreciate her alienness. He didn't fit at all with the group as a whole. It would have been different if instead of the Interloper, it had been a different character. Someone decent who treated Isabel properly, and who was younger. We might not have been happy - but we wouldn't have been nearly so outraged.
It would also have been different if it had been another show. Roswell implied promises other shows didn't make. Roswell was built in large part around three human-alien couples. Gazers tolerated coming last in screentime, we tolerated nonsensical interruptions, and then we lost everything. It was a real betrayal. It was one that shows such as Buffy avoided by making the opposite - ever-changing relationships - clear from the start. (I still hate that they killed Tara. I think it was a horrible decision.)
It would have been different if it had been handled better. If there hadn't been an onscreen break-up, a pointless and out-of-character relationship with a stupid old guy, if Alex and Isabel had been back together longer before the end. If they hadn't put horrible comments into the mouths of Isabel and Kyle, vicious and completely unnecessary attacks on the show's fans.
It would even have been different if anything else in S3 had been done well. If we could have enjoyed the ohter characters or couples - but they were destroyed too. If there had been interesting plotlines - there weren't. If the show had been funny, or exciting, or had any interesting science fiction, or if it had done anything with the return of Tess, or with Isabel and Max's parents finally being told the truth - but it fell short in every single one of those criteria. We had nothing good onscreen we could have attempted to direct our attention to.
Sum1, you argue that Roswell was better than other shows. It was, once. But then it fell, and the heights it had once attained only made it worse. Roswell became worse than anything else on TV. It betrayed its premise, its characters, and its fans. Criticisms about S3 aren't nitpicking about a great show making mistakes. They're complaints about a once-great show becoming a mistake, one massive hole of plot discontinuities, character inconsistencies and bad ideas.
