There is a more general issue that applies to specific provision in trains for specific groups or needs, whether it's play areas for children, bike spaces, full restaurant cars, wheelchair spaces, etc, and that is that the demand for all of these is extremely variable, and often the relevant passengers will only be around for a small proportion of the train's usage, whether it's by time of day, route, season, or whatever. The rest of the time the provision is wasted. Seats are a fairly basic requirement, and the railway is (somewhat) able to manage whether a 4 car or 12 car is required, but putting in special needs provision that is only used a small amount of the time is just wasteful.
Most trains I am on allow bicycles, but there aren't any, especially in the winter. I think the demand just isn't there.