I keep seeing this opinion and whilst I agree, in reality it would not work because Cobie Smulders has moved back to NY to be with her family something she has wanted to do for a while and was waiting for How I Met Your Mother to finish.
She won’t be on Agents of SHIELD full time, she might turn up every so often. Hill as Director might seem like the right choice but real life circumstances means it can’t happen.
I get that fans are annoyed but its like those saying Tony should be Director, as if RDJ is going to turn up on AoS every week. Not gonna happen.
And its clear going forward this is the story of SHIELD being rebuilt from scratch so the Director would need to be full time on the show.
Hence Coulson being the logical choice, you could argue for Melinda but out of everyone on that show Coulson is the one that has the biggest faith in SHIELD, and belief that it is needed.