The Steemit interface (Steemit is the interface) is not going to be developed. Steemit Inc that owns the interface is not going to develop the interface any further. Steemit Inc is focusing on scaling the blockchain as it should be. There are many other front ends that serve different types of needs perfectly well, including Steeve that you mentioned. I know Steemit is still the most popular front end but I think the use of the other front ends should be encouraged.

@steemcleaners was not created to weed out low quality content but to fight abuse such as plagiarism. Quality is a highly subjective matter and it should be left to the community judge whether or not a particular piece of content is low or high quality. Anyone can upvote or downvote depending on whether they think a post is getting too much or too little in the way of rewards.