Despite arbitration clauses in the EULA, there are people who can sue. The buyer of the device may be barred from suing, but other parties who suffered damages can still use. Roommates, guests, family members, people who live downstairs below pipes broken due to a Nest failure - they can all sue. They didn't agree to the EULA. Regular negligence standards apply. If you can show that a lot of the things failed all at once, that's a pretty good case for negligence.

This can also come up in landlord/tenant situations. If the landlord put in a Nest, and its failure caused the tenant problems, like having to spend the night in a hotel, the tenant can probably sue Nest.