The flow thing was just an example. The point was simply to illustrate that we shouldn't reject out of hand the idea that an ordinary artificial language (as opposed to mathematical notation or something) could retain its regularity.

The point is simply that the evolution of the language directly depends on how it starts, which means that you could design in such a way that it drives its evolution in a useful way. Just because it would evolve doesn't mean that it would lose its regularity. The flow thing is just one example of many. If it flows well, that's simply one thing to not have to worry about.