Extensive pocket configurations (5+ pockets) aren't necessary for most riders, but they really shine for bikepacking, touring, and long commuting rides where you need to carry tools, snacks, a phone, extra layers, and other essentials without relying on a backpack or frame bags. Cargo thigh pockets give you easy on-bike access to nutrition or your phone, while zippered secure pockets keep valuables from bouncing out on rough roads.
The tradeoff is weight and bulk. Overloading those pockets can cause items to bounce, create chafing on longer rides, and even affect your pedaling motion. More fabric and zippers also mean slightly less breathability.
If you typically ride with a jersey or a small bag, you probably don't need this many pockets. But if you want to ditch the backpack on self-supported rides or carry everything on your commute, extensive pockets can be a game-changer.