It is difficult to forget or get "rusty" on something one has never acquired properly. I believe hand flying basics get to be learned from the very first hours in one's flying school. After that, one is supposed to build up on experience on those basics and later on eventually adjust it for the type of aircraft he/she is flying.
Hand flying should be allowed and even encouraged in airlines, as said above : choose the place and time.
From my experience, I am amazed how many experienced pilots just got through the "net" into airliners, with below standard raw data and hand flying skills, to the point that landings really look like controlled crashes. This situation of course being aggravated with the "Bus"type of automation where you actually never fly manually the aircraft, unless you go into "Direct law" following some failures.
I havent seen many guys doing a proper raw data ILS with a "Bus" with all the automation and Flight path vector taken out, although I reckon it might be a little bit of a hard work, due to the sidestick type of flying philosophy;"No FPV ! Kamikaze type of flying" they say in the airline I work for. Kamikaze may be, but the FPV is just another FD, and there goes your raw data hand flown approach.