Honestly, I use WiFi for low-bandwidth, mostly text, stuff. It makes it possible to look up basic trip information on the Internet while I'm on the train, which is invaluable if I need to reschedule something. It makes it possible for me to check things which I need to check for work purposes. I could attempt to do this with the miniscule screen on a cellphone, but it's obnoxious. I could set up the complicated tethering where I use a cellphone as a WiFi hotspot for a laptop or tablet, but eeech...
So I think the Wifi does what it absolutely needs to do. Additional bandwidth would be for "play" purposes, which is nice. But being able to check transit, hotel and restaurant websites easily is highly valuable and there's plenty of bandwidth for that.
The PPC Wifi was a really cobbled-together operation; the WiFi deployment elsewhere is using more serious equipment. It seems to be used over-bandwidth on the NEC (do people on the NEC hog WiFi more?), but it's doing very nicely on the Empire Service, Surfliner, etc.