Here's a few examples of how what we have onboard (or didn't have onboard) has been beneficial on RV trips:
1) Loaned our spare water pump to friends we were RV'ing with when their's failed.
2) Loaned our 12 ton hydraulic jack to a person who needed help hitching up their TT when they didn't have a decent portable jack along.
3) Loaned some unusual socket sizes to a motorcyclist to repair their bike.
4) Used our built-in roof ladder to get up on the roof to repair a cracked vent cover.
5) Loaned a flexible long-neck funnel to friends we were RV'ing with so they could refill their Class C's transmission after a near-catastrophic over-heating fluid loss.
6) Used our beach umbrella to sit under while using our extra lawn chairs to sit right at the water's edge on a beautiful sandy beach on Lake Erie.
7) Used our quiet backup portable generator (instead of the louder built-in generator) to power a large oscillating fan outside to keep a group of frineds comfortable duing a BBQ on a hot day.
8) Used our portable propane single burner stove outside (instead of our stovetop inside) to cook bacon on when boondocking along the Salmon River so that grease wouldn't get splattered all over our galley area.
9) Used our 30,000 lb. tow strap to try and pull out our friend's Class C we were RV'ing with when they got stuck in a soft shoulder on a remote highway (with poor cell phone access).
10) Used all 100 feet of our total freshwater hose length in order to fill our FW tank at a beautiful but otherwise poorly set up campground.
11) Used all 80 feet of our total shore power cabling in order to have full hookup capability at an over-flow camping spot in a campground.
12) Loaned our full power portable compressor to another camper in a horse event drycamping area so that they could blow up a low tire on their 5'er.
13) Had to tolerate very limited fresh water use for a few days on our recent otherwise spectacular RV trip due to a leak that developed in our toilet's water valve assembly. This is the SECOND TIME that this has happened to us - so I now pack a spare complete toilet valve assembly along with our other spare items.
You never know what trip altering event - that stuff you carry along could have eliminated or minimized - can occur when out and about. Why not carry the stuff along if one can fit it in and if one's rig can tolerate the additional weight?