I remember reading them back in the early 90s (Robin Hood: Prince of Thieves, Far and Away, Back to the Future). They don’t seem to be a thing anymore (or am I just not noticing them).
As an aside I remember liking them but I was a preteen at the time so maybe they were terrible and I just liked the movies.
Do you think they were bonus scenes or more like “oh crap, this book will only be a 100 pages if I don’t make some stuff up” scenes?
Most additional scenes in the novelizations were actually in whatever script was referenced.