I know that there are many factors that influence rivers colour. Still that's not really an excuse to have them dark blue as the open ocean. You don't need to simulate erosion, soil stirring or algae life cycle to have better looking rivers. Any reasonable attempt to reproduce a more likely colour would be better than what we have now.
Having said that, you're probably right and there are more important things to fix right now. It's just that with the changed scenery colour in the last update (which i really like) the ugly rivers are more noticeable. We have a saying in Italy when something sticks out for being ugly amongst other things, we say "รจ un pugno nell'occhio" wich translates litterally in "it's a punch in the eye" hope i conveyed the idea
Now i'll go and open a thread about the fact that we need darker trees
