I like the idea, and I like the current phrasing.  I think we'll end up with a system that operates more smoothly with this as a default option.  I think having to type a custom comment is sometimes discouraging for people, and so they either go with migration (when it will just have to be closed on SO), or the "not about statistics..." option (which often isn't quite true).  

I do worry about making the suggested text longer, but it would be nice if it could be more specific than "...it does not appear to meet their standards."  I wonder if something like "...it does not appear to meet their standards (e.g., coding questions need a [MCVE](http://stackoverflow.com/help/mcve))."  I suggest this because I would guess 99% of the threads that don't meet their standards do not by virtue of lacking a MCVE.