Meh. Space Mountain and SSE also accrue black mold stripes that has to be pressure washed every so often.
As an aside, this is part of the reason Disney replaces or rethemes attractions rather than add a brand new one. Each attraction has a cost for upkeep and maintenance and staffing. Once an attraction isn't pulling its weight in bringing in guests or has growing maintenance and upkeep costs, a financial decision has to be made:
- Pay for a huge refurb and keep it the same.
- Pay for a huge refurb, but retheme it to something more popular (or less 'problematic').
- Pay for a replacement attraction.
Putting new attractions everywhere when you have attractions becoming problematic... you address the problematic ones first.