I often come across sites and interfaces that make me question why something works the way it does, and I’ve often thought it’d be a fun experiment to try and improve that interface myself. But having not been there from the beginning, designing under the same constraints as the original designer(s), I rarely view it as fair or constructive. That doesn’t mean it still can’t be fun, though.
Like the last part of the article states, perhaps doing unsolicited redesigns is okay as long as you remind yourself that all of the original constraints have magically been lifted for your version of the design, rendering it much easier and free-willed.