People want closet space. If you fill it to the gills, the assumption is you don't have enough closet space.
If the garage is full of stuff, the seller is saying there's no storage in this house.
Remove the trophies, collectibles, knick-knacks and souvenirs so a buyer can imagine their stuff instead of yours.
And while you're up there doing the windows, you might want to get up there and re-caulk.