They started adding back the animated railroad crossings with the Southeastern High Speed route by adding it to signal system for that route. Now with animated RR crossings are part of the signaling systems they should add them to previous TSW 2 routes (Example CSX Heavy Haul TSW 2 version) and the preserve collection routes (Example The Long Island Railroad) as future updates.
That would be nice, on routes such as RT, RSN or ECW where there are a lot of crossings. But then, there are so many things that should be added and need to be fixed, and for me personally this would have a somewhat lower priority over fixing consist, sound and/or signalling issues for example.
While adding these would be nice, I agree that there are other things that should have high priority. Because if you are in the cab of a train, you wouldn't see crossings activate anyway.
Now that dtg know how to get level crossings to work then it will be easy to implement on new tsw2 routes but putting this feature onto preserved collection might be a bit harder