Every family is different. For us, while it is helpful to have a place to store stuff, we really don't bring that much. We had a stroller on our last trip because DS was just shy of 2. He napped in it which was convenient because we didn't have to leave the parks for breaks and he wouldn't have napped at the hotel anyway had we done so. Also, at that age, kids are so small (can get lost or knocked over easy in a crowd) and don't understand not to run off. We had a small crossbody backpack with diapers, wipes, extra clothes, and snacks which was on our person at all times (since you never know when you might need it and the stroller isnt with you) and it didn't weigh much. We had a second bag under the stroller with DD7's autograph book and markers and some glowsticks. Any large souvenirs we wanted we waited until the end of the night to buy or had them sent (for free) to our hotel.
DD7 never once complained about being tired or sat in the stroller. We took breaks for meals and snacks and tried to alternate sit down shows with rides and it worked great. For us, we find that if she gets to the point of whining or complaining (anywhere), its time to leave. If she asks to take a break, that's totally fine, but if it gets to the point of complaining, then it's time to leave and relax at the hotel. She never got to that point on the trip. We spent on average 10 hours in the parks on the days we went and alternated between parks and water parks/pool for 12 nights. We never lost her in the crowd. When it was really crowded (mostly when trying to leave the parks), she held one of our hands or grabbed onto the stroller.
Our next trip will likely be right before DS turns 4 and DD will be 9 and I highly doubt we will use a stroller. By that point, we won't need to carry diapers/wipes, so really we will only have to bring one small bag with autograph book and markers, and a couple snacks. We could carry a couple water bottles too if needed, but we generally just get the free water at QS or an occasional slushie or something and it's not that big of a deal to carry it for 5-10 mins while we drink it, or sit and rest while we drink it. Like I mentioned before, with souvenirs, we can have them sent to the hotel or wait until right before we leave to buy them.
I'm looking forward to not needing the stroller because it's so much easier (for me anyway) to navigate the parks without the added physical space that a stroller takes up. It's far easier (again, in my opinion) to get through crowds when not lugging a huge stroller. We won't have to unload and fold it and hold on to it on the bus, or search for where the CMs moved it in stroller parking, or worry about bringing the rain cover and covering/uncovering it in the rainy afternoons and lugging around a wet rain cover. We will also get to experience the parks more from DS's perspective as he can walk around holding our hand and get excited by all the little things that are often lower to the ground that adults tend to overlook. On our last trip, we ditched the stroller several times in stroller parking and let him explore walking the parks with us. It was magical seeing the things he got excited about.
Obviously, with an older kid, they probably aren't going to get excited about some of those little things, but it is a special aspect of the trips for us.
At almost 4, DS will be completely potty trained so we won't need to carry those extra items. He will be old enough to understand not to run off and he's a shy kid anyway so frankly he stays rather glued to me anywhere we go. DD at that age no longer needed naps, and DS at 2 currently doesn't take them, but if he needs them on the trip, we will hit a show and he can sleep in my arms or if absolutely needed, we will go back to the resort for a break. My kids have far more energy and stamina than I do and can out walk me anywhere we go, so I don't forsee having to carry him except for my own convenience of not having him knocked over at the end of the night by people twice his height who can't see him. DD at 7 was 48" and while still shorter than adults, could still be seen so as not to get trampled. I don't think I have physically carried her anywhere since she was under 5.
The only reasons for me personally to need a stroller are 1) Someone who can't walk due to age or medical reason, 2) Toddler/ small child who naps, 3) Someone too short who other guests might not see walking, 4) Someone who doesn't understand not to run off, 5) Stroller space for carrying things. For us on the next trip, none of those will really apply. There's also the suggestion that kids have short legs/ get worn out, but for us, those are the times for shows and snacks and meals as mentioned above. For my kids, by the time they're too exhausted to walk, they're usually too exhausted all around to really handle much more of anything, so if a break doesn't cut it, then it's time to go. I'm sure DD would love to sit in the stroller and be pushed around (I would too!) but she knows that if she wants to be at the park, she has to walk. She gets worn out, as we all do, but understands that it's part of the experience if she wants to be in the park.
For me, if I was pushing a 50 lb kid in a stroller, I would get worn out so much sooner and need to cut the day short, which would mean having to leave early when she'd still be full of energy. That would leave her disappointed and too full of energy to want to rest back at the hotel which wouldn't be fun for anyone.
That's how we view things and what works for us. Not everyone will have the same opinion and different things work for different people. I just wanted to share an alternate perspective on the subject.