Just to correct your first statement, in their recent article, they have ruled out idea that D-wave solves problems by cooling (otherwise known as simulated or classical annealing). Quantum annealing, a special case of Adiabatic Quantum Computing, is a completely different approach for solving Ising problems.
Unconstrained optimization is NP-hard problem, and quantum approaches won't change that. However, D-wave hopes they are faster in solving optimizations than classical solvers, something they haven't demonstrated yet. The fact whether D-wave is actually a Quantum machine is interesting to Computer Scientists and Physicist who care about accuracy of commercial hype, and also to D-wave's future customers.
Unconstrained optimization is NP-hard problem, and quantum approaches won't change that. However, D-wave hopes they are faster in solving optimizations than classical solvers, something they haven't demonstrated yet. The fact whether D-wave is actually a Quantum machine is interesting to Computer Scientists and Physicist who care about accuracy of commercial hype, and also to D-wave's future customers.