Under index wallets, monopoly players are able to exploit their market advantage to artificially control the rest of the market's valuations.
Index wallets do not address free-rider problems in public goods funding, as they purport to.
Index wallets economies would suffer from balkanization, where only certain sub-communities transact in a particular currency.
Index wallets do not create wealth equalizing dynamics, as they purport to.
People will maintain multiple wallets which allows them to take advantage of business owners.
Index wallets cause runaway inflation
Index wallets create highly unstable waves of valuation changes that do not settle to an equilibrium over time.
An index wallets economy suffers from frequent market failures (people unable to transact) due to differing valuations.
It's impractical for index wallet users to update their valuations, as there will be too many currencies and too frequent changes.
Index wallets represent a privacy hazard for their users: they leak information about users' values and economic relationships.