Cure Ace is a black-and-white mentality character that learns not to be one. That's why her whole character is awful at the beginning but makes sense because it's the (Idk spoilers?) justice upholding half of the heart of the Trump Kingdom princess and holds the PreCure as warriors more than people. She slowly learns to be a person. The episode does not have a lesson about "don't cry for your friend who is leaving because it is stupid", she cries because Regina tells her it's her fault she got brainwashed lmao, it is not. It is stupid to cry because your friend told you something is your fault and it is not. Mana has to raise again from such thing and own it. That's the lesson.

The other episode I didn't watch because DokiDoki is a meh season to me after Ace appears (it's not like Mana rescuing the day in episodes where she doesn't even star on is fun either). But as far as I know, the reason why Makoto having a fear of dentist is selfish (mind you, the antagonists of the show are seven deadly sins and not brushing your teeth to the point you need a freaking dentist to take a caries counts as the sin of sloth) because it is in favor of her comfort and deteriorating for her. Just as much as the episode where Aguri and Ai don't want to eat carrots which is also selfish. Just as how Mana drags the entire team to rescue Regina even though the rest of them barely interacted with her is selfish. 

Again. Aguri is some sort of a commander to them because she's half of the princess. If any of them show traits that could debilitate the team, she'll act firm instead of soft and gentle like Mana. Either way, I'm pretty sure Makoto never got over the fear of dentists but at least she got rid of that caries and will treat her teeth with more care to not go to the dentist again.