Wow. I'm sorry to hear this. Of course no one can tell you how to feel, but I'd hope you'd be able to start a new tradition in honor of your parents. Obviously we on this board don't know your personal situation, but I'd hope that you and sibling, child, partner, friend, or whoever could start a new tradition of visiting the parks. If your reasoning was being upset with Disney and didn't want to consume their product, that'd be understandable and I wouldn't question it; however, I'd think your parents after their time comes would want you to continue to enjoy the parks for the memories, and also in honor of them. After my dad passed 21 years ago, there were tons of things I could've decided to no longer do because they reminded me of him. Instead, I decided to honor him. One example, on the night of my wedding my new wife and I decided to stay overnight at the hotel that not only we met at, but my dad worked at for roughly 25 years. I worked their with him for 3 of those years. Tons of memories there, but we did it in honor of him. We had our reception at our favorite venue, but it was his favorite restaurant as well. You're very lucky to still have both of your parents at this point in life.
That said though, each person is entitled to grieve how they are most comfortable. I hate hearing that anyone would stop visiting a place they love because of grief.