It seems to be the way of the future.
To get a bit more out of a drain that has just about reached the end of its life, they are now shotcreting them (this has been happening for a few years in Melbourne and maybe longer in other parts of the world, but they have definitely recently taken it up a level). In every example I've seen of this, it has been to the detriment of exploring (and graffiti if that's your thing).
In one tunnel a nice red brick drain that taller people could make their way through, is now covered in concrete poo the scrapes the crap out of you.
Although I didn't film a close up, you can see what I mean in this 3 minute video.