This is an ongoing thing and I think it's easily mitigated by just hiding the ratings of ongoing dramas.
The problem: Drama discussions become dominated by discussions of the rating. And minor fluctuations are debated and dissected. A rating too low on an airing dramas (despite its actual merits) turns off viewers who might have otherwise given it a chance.
At this point I just see ratings on airing dramas as detrimental and a distraction from the dramas they represent.
I propose we either:
+ Allowing rating but hide the results until it's complete
Or
+ Not allow rating at all until it's complete and anyone who liked it or disliked it enough to rate it can come back
As for users being able to decide whether or watch a drama or not, reviews and comments are still available so I don't see the overall star rating as necessary for airing dramas (especially, again, because it does fluctuate).
ETA: also not o mention the ongoing allegations of rating manipulation. Despite what MDL says this is a common belief amongst users, especially when an airing drama rating changes drastically. A debate that would cease if we just hide the rating.