maybe my memory is a little foggy, but all i remember of the johto departure is a fork in the road, all of them going their separate ways. and then getting teary eyed. especially Ash crying like a little weenie. was emotional but did not seem so big a goodbye.
That's because you're an avid Pearlshipper. It's widely recognized that Misty when she left declared her true feelings towards Ash: 'Ash Ketchum, now I know how you truly feel about me'.
Also Misty was heartbroken when she found out that she had to go to Cerulean to keep the Gym running. And when she had that threeway battle together with Ash and Brock to remember her that they will be best friends for ever. Then Misty's song, which examplifies how much she cared for the group: 'What makes me misty most of all, is that I can't see you at all'. That combined with the lines that speak about her travels with all of them really said a lot of this group. Then her telling Ash to always do his best and to not forget his morning ritual, and telling Brock not to get to sidetracked by girls in a cool and collected voice... sigh.. Then there's the bicycle thing that kinda always was the thing that supposedly was the reason why Misty stayed with Ash. But even when she got her bike, she rather wanted to stay with Ash eventhough there wasn't an issue anymore, aside from being best friends. I'm not even a shipper, just so you know.
Also from Brock's side. Brock received an email prior to this parting that he had to do some business in Pewter, but he didn't say it until the last moment, because he didn't want to leave at all. Misty then says that she understands because she doesn't want to leave as well. This is the kind of friendship that made Ash cry. It was on a different schale then how he was friends with May.
May chose to leave on her own. Brock and Misty had to leave. That alone is a reason why this send off was so hard. I'm guessing that Dawn will live on her own volition.. since nothing will ever come close to the group being literally ripped apart like that.
May, and probably Dawn, had/have something to look forward to, but Misty and Brock at the time actually wanted to continue with Ash and favoured that scenario as evident by the conversation at the crossroad.. Three friends were cast into their own individual scenarios and two of them would probably end up sighing when they'd remember the times with Ash and how it could've been if they stayed with him, which is why Brock probably returned (discounting the writers input, but just him as a character).
That being said, please let this just be something better then Ambipom's send off.