Justify using Wordpress? I guess people use it because it's easy, it's included with cheap hosting packages (or you can have Wordpress host it for you), and the huge variety of plugins make it flexible.
It's possible for almost anyone to set up a quick blog with more features than, say, Blogger. I don't know how it compares with the point and click setups (maybe Wix, judging purely by their ads - no personal experience to judge), but that's the justification. People don't care about the details - they want a pretty website easily and quickly.
I'm sympathetic to that, but less sympathetic towards businesses that rely on Wordpress, shoehorning shopping carts and other add-ons onto a platform that really isn't designed for that kind of content.