The line between complex and convoluted is paper thin. I look at convoluted as being something that is not fully explained. Or twisting something to make it seem like something it's not. Which is not at all the case with Final Fantasy VII. Everything in the story is fully explained. There aren't any "Guardian Forces made us forget stuff"-sized plot holes, and the only thing convoluted would be the poor translation. And that is certainly not the story's fault. Of course, that's only how I look at defining it.

And part of why the story lines of games like Final Fantasy VI and Final Fantasy VII are so revered and have withstood the test of time is because they touch upon mature, deep, and complicated situations. That they touch upon them is fact, whether or not you can relate, or find any entertainment value in them, is your own personal opinion.