I think if the developers want to change a character, then it's their prerogative (even if in this case, changing the raid boss sounds like the most efficient way, rather than completely changing a good character that has been used for years)...
This said, it is also only fair to refund everyone who put a zeta on Finn (and gear maybe).
This last line of "Zetas will not be refunded" is what is angering everyone. To a lesser extent, the character change in particular.
You shouldn't treat your costumers that way. This only hurts your business.
Please reconsider (if not this character change), at least the zeta investment. It's not worth angering 90% of your player base over this very minor issue, now, is it? It will cost you nothing to do so. But it will cost you a lot if you don't, I think.
