Even trivial changes consume project resources and resources are finite.
Implementing a low priority change takes resources away from higher priority changes and unless there's something wrong with way changes are prioritized I can't really see how one can justify that.
The really hard part is weighing all the different factors when calculating the priority. Giving a ticket priority just because it's old doesn't make much sense. But if the age will cause enough customer dissatisfaction that it ends up having economical consequences then it might make sense. Apart from that I don't think age should be a factor. Each time we go through our ticket list we look at it fresh: At this point in time, what is the most important change for us to focus on.
In my projects it's common for trivial but very low priority changes to be rejected. I think it's better to let the requester know that there's minimal chance their request will ever be granted, given that there will always be more important changes to work on, than to give them false hope.