Some templates have matching parameters (e.g., almost everything built on {{ambox}}). It would be nice to have a "Change template" option for switching templates without re-entering parameters.
This will work for some citation templates (at least for the most commonly used parameters) and for most maintenance templates.
Setting to Low priority because we don't yet let users change which parameter a value is assigned to (e.g. change {{foo|1=34|2=56}} to {{bar|fish=34|bang=56}}).
Why not allow to change to any template? If the user choose to change to a template with not matching parameters, it up to the user to fix that.
I think that even if you change to a similar template, it is a big chance that it is one or more parameters that do not match.
So maybe, the user should allays be warned that he/she should check all parameters.