Also it seems that those in favor of the ending in particular hold a personal connection to the outcome of the relationship.
That also factors into how you feel about the ending.
Just to make myself clear, the relationship is what it is. My point is that the series ended sluggishly with the revelation of said relationship which had no relevance at all to the series as a whole. It was forced by the powers that be for this series, hints or no hints.
The good thing about this is that it leaves no loose ends to the main plot and leaves room for imagination on what is next with Korra as the avatar.
Maybe nitpicky or whatnot but my point stands.
Anyhow, that is my opinion on the ending.