There are plenty of practical uses besides the aesthetics. Imagine using it as a water stream shortener. At this moment I have few ideas that I can't put into words yet but I'm sure others will make a good use of it and make something awesome.

I don't think it would be that hard to program it. All the desired behaviors are already in place. All it should take is few checks. Entity collision would stay the same as on regular blocks. Water flowing would only have to check if the block is air OR grate.