I guess the amount of characters makes it look like progress is being made slowly, because the majority of characters won't receive new scenes whereas only a few do. If your favourites don't happen to be among them, it is a bit frustrating. Since the dev cycle is rather slow, with only one or two updates a year, it makes it look like the game doesn't move in any direction.
I am not sure how once could adress this, since the dev is clearly transparent about his work and his progress. Maybe it will take a few years to finish everything, but I have been following this game for years and will continue to do so. If there is anything to complain about it is that the pacing of the game has been rather slow in the beginning and went from zero to a hundred in one single update. It felt a bit rushed, IMHO, but other than that the game is one of the better ones out there.