I'm glad to hear that versions after 5.10.0 started doing what I would call the Right Thing-- somehow I missed the change. Myself, I'm still usually specifying version 10 in the code that I write, but then I generally create code using templates that also have "use strict" and "use warnings" lines-- you don't care much about a few redundant lines when you always start from the same template.

And in any case, any of the modern object systems are going to turn on strict and warnings by default.