From what I have read, Flurry II (and the -EVA thing, of course) makes it quite useful for RNG setups. It's ok to dislike RDM, but there is no reason to be aggressive towards it and say it isn't useful, when that clearly isn't the case.
Whether it is necessary, well, there are alot of things in this game not "necessary" so it is not worth talking about that. It is, however, useful, possibly even optimal in certain cases.