As to item 2 above, that seems a tall order that not even RL is able to achieve (given the posting date of the OP). A developer may be on vacation, it may be the holidays, or there may be personal reasons that an immediate response is not possible.
Also, there should be some allowance for free items, where I believe it is reasonable that there will be no customer support.
My feeling is that this has been introduced without much thought or input from developers.
As a user I see the no value in adding responsiveness as a factor. Frankly, initially it wasn't even clear what this was for until I saw this discussion...:unsure:
Also, a flawed rating system as has been pointed out is of no use. I rather see a reporting system where issues can be sorted out between user and developer before negative ratings.
On-line reviews in general are a mixed blessing as indeed users do not always inform themselves of what they are buying.