I appreciate your points, please allow me to make a sub-point.
Splash Mountain isn't hurting anyone, it's association with a film is what is upsetting. We can already see how this is a much murkier territory than people who physically are unable to go on a ride. For example, you say this leads to a better experience for all, but I fail to see how that is the case. A group of people (at least equal to the ones that are offended) are saying this will drastically decrease their experience with a beloved ride.
Now, it is a completely subjective value, but how many people need to be offended before it demands action? That cant be answered, hence debate.
This also brings up other difficult questions. Can good art come from bad art? Is it better to build something new and keep it next to the old, or must one be torn down? This doesn't even approach questions such as Disney's legitimacy in their anti-racism statements when they continue to do flagrantly racist things in other countries, as long as it brings them more money. Hypocrisy deeply upsets some people.
I appreciate your perspective, thank you for reading my own.