Yes, they are worth having. Apart from the reassurance of knowing that there is one to hand, they are useful sails even in less than a full gale. I suspect that a lot of people knock the daylights out of reefed furling genoas in fresh-strong winds when they would sail better if they hoisted the storm jib.
Strangely enough, we have NEVER used our CD player. We have taken CDs with us on weekends and summer hols, but never seemed to have time to play them. Other folk play theirs all the time, even on the water. One loves to pretend he is in Apocalypse Now, and plays the ride of the valkyries every time he clears port...ugh.
<hr width=100% size=1>Black Sugar - the sweetest of all
Could be worse. My girlfriend at the time insisted on playing ABBA all the time while we were sailing in Sweden. Embarasing doesn't even begin to describe it.
Pity this serious question has produced responses degenerating into somthing totally irrelevant.
My answer is yes they are worth having, especially if by channel cruising you include cross-channel trips. There will come the time when every weather indication is wrong and you will get caught out in stronger conditions than you would normally go to sea in. On that occasion you are likely to be very glad of a storm jib, especially if you have a typical modern cruiser which easily becomes over-pressed.
least used bits of kit on most boats are all the expensive safety paraphenalia you hope never to use...life jackets and attached lights, flares, throwing lines, multiple electric and manual bilge pumps, etc, etc
you have a detachable inner forestay. Most AWB boats that you see around on the seas today have but 2 sails: a furling genoa and a non-reefing main: and neither are used much.