Remember this is an MMO, an MMO thrives on players staying for a long time. If you lower the SHiny chance, the probability that many will quit quickly or play less because it is too easy increases.
Furthermore, we should consider that Shiny hunten Much RNG is a small example from me.
I never found one in the official Pokemon game, although I often played the game for 999 hours. Here in the MMO I have 71 shiny out of 10k hours of play, that's about 1 shiny in 148 hours. now please tell me this is not ok for an MMO?