Right, but the old Windows logo has a distinctive shape. Even in black and white, it's distinguishable. Now you could argue that it's just squares that have been warped with a wave and I'd agree with you. However, the important part here is that they've now simplified it further in the direction of even less unique. That makes a trademark even harder to defend. That doesn't mean the shape has to be complicated: I'd argue that Nike's swoosh is extremely simple yet has just enough going on to make it instantly recognizable. The old Windows logo was another decent example.