I am sick of that line being used to defend the episode. You don't move onto the next storyline without resolving the previous storyline. You don't leave things set up so that the audience can take a guess about what happens, you finish the storyline. This is the one cardinal rule of storytelling in any form, be it TV, movies, books, newspaper comics, caveman drawings, whatever.
But for all intents and purposes it was resolved. Everyone knew what happened next. The real conclusion was Matt realising what needed to be done to restore things, given that we'd seen them come through the gate after a message twice already, we didn't need the tedium of watching them do what we already knew they were going to do.
Call me old fashioned, but I prefer my stories to be wrapped up all properly. By your logic, it would have been okay if The Best of Both Worlds Part 1 ended the same way it did (Picard assmilated and Riker ordering Worf to fire), but then the next episode having Picard normal and in command of the Enterprise and nothing is mentioned about his assimilation. After all, we knew Picard was going to be rescued by the Borg, did we really need to see it happen?
Hell, SGU's mid season cliffhanger has Destiny being teared apart by aliens and nearly destroyed. Maybe the next episode should just have life back to normal. We know they're going to make it out okay, do we really need to see it happen?
There's a pretty big difference between knowing something will happen, and knowing how it will happen, I'd have thought that would be obvious. We knew exactly how the situation was about to be resolved, and being an AU we'd already seen how it would affect the characters. There was nothing else that needed to be shown, which cannot be said for the two examples you provided.