The benefits:
Breakfast as soon as we get up and are ready for it. No figuring out what to grab on the way to the parks.
Coffee etc you can take back to your room while you're getting ready.
You can pick up fruit, snacks and drinks and fix bagel, cheese, and meat sandwiches for lunch and take them into the parks.
You can also come back to the hotel for a rest and enjoy the snacks and drinks in the lounge. They have delicious homemade potato chips.
They have hot appetizers and desserts in the evening. You can enjoy as much beer or wine as you want.
They have a cool coffee machine that makes all kinds of espressos, cappucinos, etc.
They have always catered to my kids, fixing them special things and just being super friendly to them.
They can make reservations for you and correct problems.
My family can make the concierge lounge work for most of our meals, though we also have favorites in the parks so we don't do the lounge exclusively. We like to rest at the hotel and we don't stay in the parks all night, so that works well with the lounge, also. You can watch the fireworks with piped in music, but I've never done that. And you can make mimosas! That's pretty cool.
All that said, you have to figure that for most people, concierge is a luxury and not a cost savings. You do it because it's convenient and kind of fun. My family actually comes out pretty close on cost since there are 5 of us and the extra cost for concierge isn't a waste with the way we use it. For 2 people, it wouldn't be harder to justify, I think.