This guy can help explain the reluctance.
Surprising, we know.
“We cannot get new banks to join the Libor panel. This is unfortunate from my perspective. But you can understand the situation of a bank chief executive who has to explain to shareholders why it should join a Libor panel given the past,” said Finbarr Hutcheson, president at ICE Benchmark Administration, speaking in London at a recent conference.
ICE Struggles To Get More Banks on Board for Libor [WSJ MoneyBeat blog]