The other gear you have also should have casters but especially amplifiers.
I don’t think you mean ’casters’ as they are wheels and that’s a tough thing to pull off trying to attach a wheel to an amp or other components . I think you meant something like Vibrapod Cones? But I do agree that casters or wheels are perfect for attaching to the bottom of the component stand for ease of use and getting to the back of the rack/component stand when making changes and adjustments. Especially if the rack is one vertical piece of shelves. Which makes said rack very heavy indeed.