it would be a shame if it was just seen as a profit making measure by airline operators
If it is a profit making measure by the airlines - Why shouldn't it be? 
When asked for tap water, I serve free of charge tap water from the potable water tap in the galley - with a smile and a sweet attitude. If customers prefer bottled water, then it is available for purchase. That seems to be a pretty reasonable arrangement, and I sleep untroubled at night as a result.
Presumably, somebody will now explain why I shouldn't sleep that well? 