Availability is not a problem, until it is. Right now there are three public coordinators that could be compromised, attacked or shut down. Even when I am sure new coordinators would pop up in case of mayor disruptions, and I am also sure liquidity will eventually find its way to the next coordinator, the process is slow and painful because requires users to choose a new coordinator.
Running a coordinator in each Wasabi client would make the whole system more resistant and would remove the easy targets by distributing the load of coordinating transactions.