There are a few problems with this.
Using CSS @import in an external stylesheet can add additional delays during the loading of a web page.
Media Query support in IE
Note: Doesn’t work on @import’ed stylesheets (which you shouldn’t use anyway for performance reasons). Also won’t listen to the media attribute of the <link> and <style> elements.
@import rules are not supported by respond.js
A solution to this could be to copy the media queries from the parent theme and include them in the child theme but this does not make it easy when there are changes in the media queries.
This is not really a huge thing but it does make it easier to disable loading the parent stylesheet.
Now for the solution. Instead of using @import just add this PHP code to the functions.php of your Child Theme. If you don’t have one, simply create new file and name it functions.php
Here is a variation that add the current parent theme version to the stylesheet url.
There might be in some themes where the child theme stylesheet will load before parent theme style sheet. Those themes will have the code like this in the header
For those cases add this PHP code to the functions.php in the child theme.
In the perfect world the parent themes would load the stylesheet like _s does.