Disney rises to the occasion better than most companies, which is what we're seeing here. I don't think this decision was made based on a petition, nor do I think petitions will stop the company from going through with what they see as the right thing.
People who go to Disney do so because that's the type of vacation experience they love. No single attraction (unless it's a new attraction with a fan base, which is a good thing for Disney) is going to impact that decision and Disney well knows it. You can write and call all you want, but the bottom line is that except for an insignificant few, no one is going to forgo a Disney vacation simply because they re-themed a ride. Most won't know or care about what happens or bother to ask why. I'm not talking about the people who care enough to post on this thread, but we are a very, very small number of the guests who visit WDW. Disney absolutely does care about its image - but the image it is seeking to project is not necessarily the image some people here want to see. Disney is choosing to align with people who want to see a different image, one not rooted in the past.
For the record, I doubt anyone had deep-seated issues with the ride's theme. That is no reason to keep it forever.