1) Travelling with kids? If you are, then park hopping may not really be in the mix if they are young ones. The option is much better if you are travelling with older children and adults.
As a blanket statement, I disagree.
It all depends how you travel with young children.
If you like to go back to the resort in the middle of the day (pool, rest, etc.) and then go out again in the evening, then the park hopper feature is especially attractive. Think about it ... it's 4 or 5 p.m. and you're once again leaving your resort to go to a park ... it's not a useless option to have a choice of where to go instead of having to go to the same place you were already at earlier.
For me, the PH is attractive for 2 reasons:
1) We travel with young kids (see paragraph above).
2) In the final few days of our week there, it's nice to be able to go to more than one park in a day, so that we can do a "greatest hits tour" -- catch what we missed earlier in the week, and/or have one more time to do the stuff we already loved. In other words, let's say during our Animal Kingdom day we didn't want to wait 2 hours to ride Expedition Everest and FASTPASSes were sold out. On a later day, we can go to AK first thing in the morning specifically to ride Expedition Everest, and then maybe grab FASTPASSes for it as well, go over to Dinosaur and enjoy that, then grab a snack, go back to Expedition Everest with our FPs, ride that, then leave. Catch the bus to TTC and then the monorail to Magic Kingdom, or catch the bus directly to Disney's Hollywood Studios for more Tower of Terror and Rock 'n' Roller Coaster, or whatever.
No, I don't think the park hopper is a MUST, but it makes things easier for us.