One of my gripes with both MacOS and Ubuntu is that it’s harder than it needs to be to grab a window corner or edge to resize it. IMHO, designers are choosing form over function.
Mac batch image resizing FAQ: How can I "batch resize" images (photos) on Mac OS X (for free, preferably)?
A long time ago I wrote about how to batch resize images on Mac OS X from the command line in my How to batch resize images on Mac OS X using ImageMagick. That approach is fine for techies who don't mind cracking open the Mac Terminal application, using the Unix command line to navigate to their folder, and then process their images. But what about regular Mac users, those who don't want to ever see a Mac Terminal window?