We've already had one similar example in Next Gen's "Yesterday's Enterprise", where an event altered 22 years in the past led to a present where everyone but Worf was where they "should" be on the USS Enterprise, despite the enourmous difference of a war with the Klingons (that the Federation was losing) raging on for most of that time.
Actually, not only was Worf gone, but so was Troi, and Yar was
there. That showed at least a modicum of thought about who should and shouldn't be there. With the new movie, the goal seemed to be just to shoehorn everybody in there, without any of this thought. Had maybe Chekov not been there, and maybe someone like Number One been there, then it would have been a little bit easier to swallow.
That the Enterprise would have been in the same place as it's prime-verse counterpart to witness the Enterprise-C arriving from the rift is incredibly iffy. The exact place it needed to be to put things right.
A decent point, but how do you know it was the exact same place?
At any rate, the intro and outro of the episode are a little bit clunky in more ways than just this, but they needed a way to frame the episode around Guinan, and showing the Enterprise in our regular timeline was the dramatic way to do that. Not every character was necessary in this movie, nor did their gathering need to be so blatantly coincidental.