-W is really short CD actually. 2.8s after Q is counted at max. Easily enough to be spamming sheen.
-W is clunky as hell to use as you lose distance if you don't use it during a knockup and easy to dodge if you try to use it as a ranged spell because you can't move during it.
-Xins squishy as hell 2 damage items relies on your ult being effective or you being really fed and probably both
-Theres actually a decent argument for BC in that you can technically focus the front line thanks to your ultimate, and use your next E if they try to get inside your ult range. But in that scenario trinity is also quite good.
-Maybe titanic hydra is better than both BC and trinity since you like the extra burst and effective AD, not sure how valuable CDR is.