No, formatting the hard disk is not bad for it. In some instances, I suppose it can even be argued that it could extend the life of the hard disk, at least theoretically.
Formatting is only doing a read/write action on the disk. The higher level of formatting, the more read/write action you would see. Theoretically, someone could argue that this does put wear on the read/write hardware, since that hardware is designed to work for some huge number, but a finite number, of cycles. So, compare it to a car. Let's say your car is designed to go 200,000 miles before the body has flexed so much it begins to fail from metal fatigue. It might fail sooner, but more likely will last longer. All that formatting is doing is using up about a mile out of that 200,000 miles. Not very significant in terms of wear, yes? The wear that you incur is so tiny, it is probably equivalent to no real wear.
Another tool - defragmentation - can even reduce long term wear, since it can reduce the distance the hardware travels to do a read/write action.