Very true. Loco shots are all very well, but we should turn our back to them sometimes and record the other detail just as much, cars, billboards, passengers waiting, track detail, coaches etc. I never cease to be amazed at how short sighted even the best photographers could be in the 50's and 60's, focussing almost exclusively on locos, forgetting all the other paraphanalia that really set the image in its time.
If you're at a place that you've been to a million times but you haven't recorded it then photograph it there and now. You never know when something that you take for granted can just disappear overnight.
Classic example for me was Ennis semaphore signalling. I photographed it on a Friday evening as it was to be removed the following day. Went down the following morning, thinking i might get a few last shots, and not a trace of it remained. It was like it had never existed.