Not exclusively for shapes. Although shape was mentioned in the suit against Samsung, which is pretty ridiculous no matter how you slice it.
Not at all. If a patent contains measurements, is that "patenting measurements" and therefore ridiculous? No. Neither is "mentioning" a shape. Or a material. Or whatever. What matters is the full, specific combination of things--THAT is what a patent is.
People think the patent is the title, e.g. "method for powering a car." ("Wow, like cars were never powered before!") The patent is not the title, nor the summary, but the full complexity of its contents.
Look at the full details of the often-misreported patent. And also look at what Samsung has actually copied--indefensible and repeated. Far more specific and intentional than just an unavoidable "shape."
You're right. It wasn't shapes. It was rounded corners.
Apple totally invented rounded corners.
Wrong again. That was not the patent. That was a detail within a full patent.