When DD was 5 we went with no stroller. She was fine for all the walking, but what I didn't see coming was the standing and waiting. We went to
MNSSHP and we had a steady drizzle the whole night. That meant we had to stand to wait for all the parades, shows, fireworks, etc. She didn't want to sit on the wet pavement. So, while walking was fine, that standing was not. I wished we had a stroller (but wasn't going to rent one for three hours)! The standing and waiting thing might also apply for germaphobic parents who won't let kids sit on the ground.
But, that issue can be solved without a stroller, too--get a vinyl tablecloth and cut it into rectangles that will fit the bottoms of each family member. When you need to sit on a wet or questionably clean surface, spread the tablecloth piece out, vinyl side down, to sit on. The vinyl can be easily wiped dry or cleaned with a saniwipe. And they fold up super flat and fit neatly into the bottom of a backpack when not in use.
Another thing to consider--strollers are also an awesome place to store stuff and I truly never found them irksome to push, park, go back for, etc. If anything, I felt more encumbered without the stroller since we had to carry EVERYTHING.