Besides, the hopper option can be added after your arrival. If a family decides they want to hop, they can upgrade, but if they find they don't need hoppers... no money has been wasted.
A lot of people advocate this strategy, but there's a flaw in it.
Let's say you have a 5-day trip - Monday thru Friday.
On Monday, you go to MK. MK is super crowded that day, but you don't have the hopper option, soi you tough it out. And because of the crowds, you can only do about 2/3 of your must-do attractions before heading off to your lunch and dinner ADRs. But you stay all day and watch Wishes, finding that you love it.
On Tuesday, you go to MGM. As many people do, you find that MGM doesn't have enough to keep you occupied all day, so you call it a day at about 5pm and head off to your resort.
On Wednesday, you go to AK. And again, AK doesn't have enough to keep you occupied all day, so you call it a day at 3pm, wasting a large part of your day.
Thursday finds you at Epcot. You stay all day, but still feel that you haven't seen it all, and at days end you find that you simply love Illuminations.
Friday, your last full day, finds you repeating MK to hit those attractions you skipped on Monday. But you are now kicking yourself for not staying all day at MGM on Tuesday, because after seeing Wishes on Monday and Illuminations on Thursday, you are now itching to see Fantasmic!
So at the end of the trip, you consider adding the hopper option so you can return to MGM and see Fantasmic! But since it's the end, you just leave it off and finish your day at MK again. On the other hand, any time after the first or second day, you'd dismiss the idea of adding the hopper option becuas it would seem like a waste to spend the whole amount just to hop for part of your trip.
But look at all the time you could have saved by having the hopper - you could have hopped to a less crowded park on Monday and done twice as many attractions; you could have split Tuesday between MGM and AK, avoiding wasting two half-days and freeing up a whole day to repeat your faves or split Epcot into two days; and you could have returned to MGM on any day to see Fantasmic!
Had you only had the hopper from the beginning, you could have had a far better trip, utilized your time much more effectively without feeling rushed, and gotten a lot more value for your vacation dollars.