They want to because they have the props, the license is inexpensive to secure and this will allow them to...
Choose:
A) allocate more of that budget to other themed attractions, providing excellent value for guests
B) make even more money on an event that rakes in cash like a DNC fundraiser in Berkeley
If, as a treat, there are fans who haven't gotten to experience the haunted house (of which I do not doubt there are many) have a new-to-them experience that they really enjoy, fabulous.