i don't know how beneficial it is, but people seem to like it and want it. it can be a nuisance, because it needs to be scraped off of the glass with a blade, rather than just a mag float. as stated before me, it needs to be introduced in order to grow.
as for the question of a healthy tank, coralline algae has nothing to do with it. the lack of nuisance algae and cyanobacteria is a good sign though (though it's not seen in these pics, i have commented on your other post about the open top tank).