it might be more realistic, but with the schizophrenic tone and pacing of this series it just seems unnatural to circle back to this and expect it to have a similar impact.
If anything, it has
more impact. It's actually been allowed to germinate over time, something the series is accused of NOT doing earlier on (including the Hughes episode itself).
Putting all the episodes dealing with Hughes' death all together just makes it a blip on the radar, just another moment in the timeline of the characters' journey. That's how the first anime treats it. The way Brotherhood does it, it's an ongoing process. It's a constant reminder that death really is permanent and has a lasting and indelible impact on the people left behind.
Besides, the events that occur in these episodes here are pretty dependent on the viewer knowing that the Fuhrer is a Homunculus and that they actually rule the nation outright, which are both revelations that came several episodes after Hughes died. And, aside from all that, the fact that time has passed is important to the narrative in and of itself. That Mustang has been investigating the Hughes case OVER TIME is the reason why Envy is pushed to action and why Lust is keeping tabs on Havoc. The fact that time has passed is what makes Edward's words all the more difficult for Gracia to deal with, because she had time to come to peace with what happened to her husband and just had someone reopen old wounds with even more tragic information. None of this works, at all, if it comes immediately after his actual death.
Basically, to do this earlier, you have to change pretty much everything about how pretty much all the major characters behaved over the last 5 or 6 episodes.