Regardless of what you claim is the emotional norm in the ME office, I know even experienced cops run up against stuff where they just can't help themselves emotionally. They don’t let it out on the scene, or even talk about it with their coworkers for the sake of the stoic culture (probably what you have been picking up), but it comes home with them. You only need to look as far as police marriage counselors to see some of the real picture. That emotion doesn't stop them from doing what they need to do, but pretending that somehow all negative emotions can be cleanly burned away like kerosene to make work is naive. The people who try to do that get burnt out or change personality for the worse. The reality is that there is a time and place for everything, including emotions like sorrow and even crying, and one copes by allotting one’s emotional time well, so to speak.
I don't mind those who fail to control their emotions at times because it shows they are emotionally functioning, it's those who fail to have emotions I worry about; do they have no empathy, no emotional connections, are are they so traumatized and worn out they have trouble feeling anymore?
The second order of business is that you are pretty badly mischaracterizing Ran’s emotional reactions.
First, the dead body/case-based emotional reactions and the Shinichi emotional reactions come from two different sources, so conflating them as you seem to have implied in your response is wrong. The dead body reaction is fear, disgust, and empathy.
Edit: The DB react similar to Ran when there is a dead body. Flipping through a few chapters, Ran doesn't act worse than the DB, except when there is a ghost involved. Sure Conan or Mouri usually recover faster to declare that it's time to call the ambulance and the police, but Ran's delay isn't noteworthy compared to other characters.
Shinichi’s emotional stuff is related to romantic hardship.
You are misunderstanding why Ran is crying about Shinichi. Although I don't necessarily like how Gosho has been portraying Ran’s recent emotional state, it makes sense. Ran cries because she knows she must let Shinichi go. This decision making process has recently become extremely overt: see the post-Shiragami car case in the dialogue with Kazuha. Ran is aware Shinichi is on an important case, yet she is deliberately avoiding forcing him to choose between her and his case/sense of justice. She also knows from repeated romance plot developments that Shinichi would rather be with her if he wasn't doing the case. Although Ran occasionally frivolously comments on Shinichi’s deduction-prioritizing behavior, Ran does not think Shinichi is being selfish by valuing justice as highly as he does. This leads to the point of pain: the more you love someone, the more painful it is to separate. Shinichi is not just a romantic interest to Ran, he is someone she has grown up closely with for most of her life, and furthermore, Ran has been repeatedly letting Shinichi go with no sign of stopping in sight. If it became less painful for her over time, that would mean she would be losing her emotional connection with him. I wouldn’t be against this sort of development, but the way Gosho has been going, Ran and Shinichi have been getting romantically closer. As would be expected, the separation gets emotionally worse every time: more crying.
Ran has always been pretty aggressive with her karate so I don’t see the Sera thing as her losing it more than any other time. I recall Ran intentionally stopping short of putting a foot in a waiter’s face when she thought he was going to throw the Mouris out of the restaurant. Then there was the whole veterinarian Eri incident… Ran gets aggressive when she feels someone has been wronged or taken advantage of, and she definitely does get ahead of herself. It’s one of her character flaws, and one I’d rather not see go because we don’t need a perfect heroine who always acts just so appropriately. I do think the lavender locked mansion redux case highlighted how this sort of behavior makes things more interesting.