Capitalism can only exist where there is a wedge between producer and consumer. It's difficult to imagine how there
could be money in a society with replicator tech and unlimited energy supply via fusion.
A part of the problem,
in terms of the plot of the show, that I have with no money (and also a limitless replicator too) is that it makes things way too easy.
Having money introduces complexity into the world we're watching on screen.
Without money there is no trade (or little) in the Federation, no little private freighters by the tens of thousands everywhere, no pirates to be protected from, no competition between Federation Members, no businesses as businesses, to names a few things the show would get from clearly having money as a consideration in the background story.