Yes, but if setting up a masternode only exist in the hands of the few then we have the same problem as the banks. Not anyone can open up a bank.
It isn't "in the hands of a few". Masternodes are as decentralised as any other nodes, there's just fewer of them (as with full nodes in Bitcoin).
"Centralised" = Recourse to a central authority is required to set one up
"Fewer of" = a numerical comparison of population
Slight difference.
The significant issue here is'nt the numerical quantity but whether they are decentralised (as in new ones can be configured anywhere, anytime by anyones without recourse to a central authority).