I don't think anyone saying anything bad is inherently biased or unwilling to accept change, but I do think some of the arguments against this decision are a little bit overly stubborn. I think it's valid to wish they found a way to do this while keeping the river, but the people who're completely against any sort of overhaul or change to Frontierland period, whether it be this or something else, I do think are being ridiculous and are completely unable to get over their own biases to see that something needs to change.
As for complete trust...well I mean I don't have complete trust because I don't have complete trust in any mega entertainment corporation to do anything. Their theme park products, movies, or whatever else can disappoint me and have disappointed me in the past. That said, I can count the new attractions and experiences they've added to the parks in the last few years that let me down on just a few fingers so I have more reason to be optimistic than pessimistic at the moment. I've greatly enjoyed most (not all by ANY means) of what they've done recently.