On our last trip, we had hoppers simply because it was a requirement of free dining, otherwise, we would have done without. We hopped once (last minute decision) after Epcot closed to go to MK for evening EMH only because we were trying to get one more ride on Splash (not for the toddler) during the trip before it closed down (and of course it closed early so that was a waste). We used the monorail to hop and frankly thought that it was a huge amount of added walking and time out of one park to transportation and into the next park. We had originally planned to hop on our last park day around mid-day (again, from EP to MK so we could spend our last evening there), but after our earlier experience with it and how long it took, we decided it wasn't worth it to waste park time trying to leave and go to another park.
I could see hopping being worthwhile for people who take a mid-day break at their resort as then you could go to a different park after the break with no more time spent than if you returned to the morning park. We don't leave for breaks though, so that wasn't a benefit to us. Also, if you have a car and don't have to rely on Disney transportation it might not be as big of a pain, or with older kids/adults. In my opinion, the extra time on buses/monorails to hop just isn't worth it with toddlers when we could just be spending that time doing things he enjoys in the first park.
Think about how you plan to tour the parks, how many park days you have, whether you will have breaks at the hotel, where youre staying, what transportation you're using, etc, and how much time it would take to park hop. For some families, it's a great option that lends flexibility to their park plans, but for others, it doesn't fit in so smoothly with their touring style and is just not worth the time.