Yep... for example Desmond said Ana Lucia was not ready yet. Probably first, she had to resolve her issues with losing her baby and then killing the guy who caused it for revenge. Only after that she could move on. Probably she had more important ppl in her life outside the island.
Same with Faraday. Desmond told Elosie that Faraday wont be going with them coz probably he'll go with Charlotte and his mother.

The ppl we have seen at the church was connected to each other and bonded in a deeper way. As Christian explains Jack needed them to move on and they needed Jack to move on. Jack was the missing puzzle piece and once he had his awakening the puzzle was complete and they were all ready to move to the next stage (whatever it is)

In that group of ppl, other then they all being friends and having a very important place in their lives, some of them were bonded in a more deeper way. Some were soulmates. Jack&Kate, Sawyer&Juliet, Sun&Jin, Desmond&Penny, Charlie&Claire etc. That's why soulmates have a part in each others awakening.

I've been thinking of why Aaron was a baby...
My brother says its bcoz Aijira plane never made it off the island and crashed. And bcoz none of them has seen Aaron growing up, he was present as a baby.
I dont know really...

Why Ji Yeon or Charlie (Dope baby) were not there?
Coz those 2 ppl did not have importance for all the Losties.
Ji Yeon for example spent her life without her mother and father around. So its normal that once she dies she wont be needing her parents to move on but other ppl who had an important role in her LIFE, whom she was connected to.
And Charlie... who knows maybe for him his own familiy (wife, children, best friend) were there to move on once he's ready.

Its not about not "loving" the ppl who're not there when you're moving on but more about "needing" the ppl you're connected to.