I think the decision to make ADR's really just depends on how flexible you are with meal times & what/where to eat.
If you are the type of family who doesn't care where you eat and really just needs something to fill your stomachs, I'd say don't bother making ADR's. Many people do it & they are fine. When they get hungry, they check out their options & either get lucky with a walk-in or opt for counter service, where you can actually get a decent casual dinner if you do your homework!
BUT, if you have your heart set on eating somewhere specific, the thought of eating counter service for dinner would totally ruin your night, make your ADR's.
All that said, you can often get lucky with last minute ADR's if you plan it correctly. My parents went on a WDW trip a few months ago & didn't believe me when I said to make ADR's weeks in advance (and they are the type who do not enjoy CS meals for dinner & do not like to eat dinner before 5pm or after 6:30pm). My mom finally called 2 weeks before their trip and could not get anything! They were very disappointed

One night they headed over to the Pepper Market at CSR & enjoyed it (it's more of an "upper scale" CS) but the 2nd night they went to AKL to visit & just for the heck of it walked up to the Boma podium to see if there were any cancellations. Well, the very nice host ended up booking them as a party of 3 instead of a party of 2 & lo & behold they got a 5:30 reservation that night!! Then the next night, the same thing happened at the Cape May Cafe!! Both of these were their #1 choices of restaurants too!
So, it can be done, but this all depends on how much you are willing to risk & what you will be ok with if it doesn't work out.