The stigma thing is not entirely true, especially before the "Korean Wave" J-drama is dominating the market along with Taiwan/Hong Kong. Drama like Long Vacation, Kamisama Mou Sukoshi Dake and Tokyo Love story was mega popular in Southeast Asia, South America, Hong Kong, Taiwan and China.
The main reason of the decline is that International distribution is usually held -back by the distributor or agency (If their talent become the main lead or main supporting cast, Especially Johnny's).
Having read the manga & watched the anime while waiting for the live action, I think everyone here pretty much…
Spot on. If there is one thing that I would change, it would be Naoto's casting. that guy is too old in the past. They should've cast someone like Koike Teppei.
just looked at your list. looks you live in bubble of kdramas. you should watch more and more jdramas. they shows…
Many of "highly anticipated" show got badly rated by the audience. I think that the main issue is their execution in "the final third", it started off really promising but it have a lackluster final arc. Viewer's high expectation also play a part in the process.
But I agree with @Menonama that we should watch what we think is enjoyable.
Since the pandemic, home/digital release is quiet fast. I guess in 5-6 month, it could be faster if state of emergency happens (I hope it didn't happen) or they formed a partnership with an OTT.
Celebrity 
The main reason of the decline is that International distribution is usually held -back by the distributor or agency (If their talent become the main lead or main supporting cast, Especially Johnny's).
Didn't expect a fast reply, thanks!
https://tv.yahoo.co.jp/review/681769?s=11
But I agree with @Menonama that we should watch what we think is enjoyable.