For me they’re 100% necessary - think of it as having 4x4 going uphill in the mountains. They are damn near critical when packing heavy loads, and in a pinch you can use them as an improvised splint or crutch in the event of things going pear shaped.
I’m running a set of Loki collapsible 3-sections that fold to about 8” for storage. I know guys who have used the costco ones successfully, but the way I have come to use mine I’m happy to spend the extra money.
One thing to consider - go with the flick-lock style if they’re adjustable poles. Way too many times Ive seen the twist lock ones either jam up or fall apart and not lock, rendering them basically useless.