I'm one who would rather wait longer and only do the Fantasy or the Dream in concierge. The Magic and the Wonder are fine without it.
I don't like the crowds, and concierge gave me a place to get away from the masses. Loved the lounge! I did use the services, and the happy hour to have a nightly glass of champagne, which was a real treat to me!
Also, when boarding, we checked in quickly, sat in a mostly empty area away from the tons of people. Boarded quickly and went to the concierge lounge. Decided to have our lunch there. I think my checked bag was there when we went to the room.
But it is a YMMV type of thing. For me it was worth it. I still have some balance/mobility problems from brain surgery two years ago, and being away from masses of people helped. I'm not saying I'll never sail the new ships non-concierge, but I'd rather save up and sail less so I can.
Now I did notice a difference in crowds from the Dream in February to the April sailing I did on the Fantasy. Definitely not a full ship. I really felt overwhelmed with too many people on the Dream. It was a three day, and people, especially kids would run right into people with no regard. I almost got knocked over several times.
So having a more quiet area with less people, snacks, beverages, made things worth it - for ME. Others may not agree and that is fine and is part of what makes the world go around. People like different things, have different things that matter to them, etc.