Note that nlwiki (for example) wishes to have *two* standard thumbnail sizes on the wiki, and is currently using the {{largethumb}} template to do this. This causes various problems for VE.
The solution is probably some more flexible method of applying named "standard image styles" to an image, which would include a default size parameter. Then nlwiki would use something like [[File:Foo.jpg|style=large]] instead of a bespoke template.