Ah, but even the Roam Church has been busy changing things since they started. New interpretations, new doctrines and all that but never, once a miracle to confirm that the changes were right. Odd that!
Going back to the Moses stories, The people should already have know the power of god by the miracles of the plagues and the part of the Red Sea. They had quite a lifetime's worth of miracles before they got to being short of water - probably caused by them forgetting to fill their water bottles. If a ,miracle was ever needed it certainly wasn't then just to provide water.
So, if god can manage the odd miracle to keep a well-miracled people in line in the desert, why on earth can't he do the same today when, in the West at least, church membership and belief are falling rapidly? Stories fro the past don't match the possibility of a miracle today. (Don't mention the so-called healing miracles the Vatican keeps recognising either as they are really dubious.)
Of course, there is always the alternative understanding of miracles - that they are the stuff of folk legend, created by fertile minds in re-telling stories. This is juts a polite way of saying that there never were any miracles and there never was any god to do any miracles. A few hundred years ago and further back I might well have been executed for writing that last sentence which shows how far people have moved on from belief. If there is a god, now is the time to show something to the people which gives them a clear way of know that there is a god as the absence of such demonstrations leaves lots of people wondering if there could be a god and deciding, probably not!