While it is desirable that a user would change the default image license for all their existing observations, it should be noted that it is also possible for them to change the license of a single image at a time. This can still be useful, especially if the corresponding Wikipedia article presently lacks a useable image.
Most users still seem to be unaware that their default image licence may restrict any possible re-use on Wikipedia, but are more than willing to change the license when asked. In over 250 requests since January 2020, two thirds of users responded and 95% of them changed their license so that it could be uploaded and used on Wikipedia. My thanks again to all those who have selected (or changed to) a compatible image license.