It probably has to do with with a lot of different things, but early CRT's drew pixels Left to Right, and Top to Bottom, so people probably started creating systems based around that. And since that is they way they've always done it, it would be pretty tricky to change everything now.
I did come up with a different solution that might work, that is similar to my first suggestion. You could write a function that takes a SFML object and a RenderTarget as its parameters. This function would then multiply the y value of the object by -1, draw it, then change it back. Then you could get code that looks like this:
window.clear();
cartesianDraw(sprite, window);
window.display()
And with the view changed so that the origin is displayed in the bottom left, things should draw as you want them to.
Have you tried to set a view with a negative height? I don't remember if it still works, though :P
window.setView(0, 800, 600, -800);