Renters insurance covers the items located INSIDE the property you rent. You take your DSLR out to the beach and it gets lost.. you can't claim insurance.
Renters covers the loss mainly due to fire/damage/theft of the rented property (that includes offsite storage you rent say PODS etc). Generally a landlord will require that from you, so you don't turn and sue them or so if their property catches on fire and you're not at fault (say faulty water heater started a fire) OR you have guests at a party you host, someone gets injured.. your renters covers any claims against you which will turn against the landlord otherwise.
For all intents and purposes, someone who underwrites a "kite equipment" policy, and realizes how high the risk is to have a kite land in a tree or on the rocks or be lost etc etc, I think the premiums will be sky high or deductibles will be high etc. The same reason Life Insurers generally don't cover Scuba or Sky diving people.
I'm sure, as with cars, your number of years of kiting experience can be modeled into this, but it's hard to demonstrate you've been kiting for a period of time etc. Also, as with cars, the kiting location bears risks, same as quoting 2 different zip codes yields very different risks and hence insurance premiums. You kite at 3rd, oh you pay 50% extra due to the hazards. You kite at Alameda, fine -10%.
Also as with any insurance, starting up you will function at a loss, until the total number of insured balances out the percentage of claims made you need to pay. I can't really see a big financial company caring of this niche because it's small, and a small company to foot the startup bills and pay the claims with the hope people get insured.. oh boy... chicken and the egg. If one starts offering this, as with many car "mechanical breakdown" insurances, you will have 1000 exclusions and gotchas and when it's time to make a claim, you realize... you're not covered.