The preceding description of the history and development of this particular heritage site possibly gives the impression of some inevitability of development, and of a smooth, conflict-free transition from a derelict industrial site to a successful visitor attraction.
However, alternative approaches could have been undertaken. Some that strike me include the following:
The site could have simply been surveyed, made safe and provided with one or two robust, external interpretation panels. Access could have been made available without the need to employ staff or provide facilities. It could be argued that such facilities are alien both to the industrial site and to the beauty of the waterfalls.
An attempt could have been made to restore the site, as far as possible, to how the tinplate works would have appeared in the nineteenth century. Such an approach has been undertaken successfully in many open-air museums across Britain.
All trace of the industrial past could have been removed in order to focus solely on the impressive natural beauty of the area. This could have allowed more interpretation of the role Aberdulais Falls has played over the centuries in inspiring poets and artists such as Turner.
You can probably think of others.