Reading magnifiers are an incredibly useful tool for people suffering from conditions like macular degeneration, cataracts, or glaucoma. Some might wonder why a person would use a reading magnifier when, in essence, reading glasses simply are two small magnifiers that can be worn on one's head. But reading magnifiers can do things that glasses cannot. For example, not every text is created in the same size, and advanced reading magnifiers allow you to adjust the magnification to match everything you read. Some can magnify a text up to 25 times its original size.
People who suffer from glaucoma often also struggle with colour vision deficiency and the dull black font set against the gray paper of newspapers can be a difficult color scheme for those with vision impairment to detect. Some reading magnifiers reproduce the text on a small LCD screen in a color scheme that's easier to read. Many models act as small reading lamps, too, with a bright LED light shining out of the magnifying glass, illuminating the text.
These types generally have a base so they can stand on a surface, and they usually have a flexible neck so the reader can bring them closer or further from their text. These lamp-style magnifiers are ideal for hobbyists who need their hands to work on detailed tasks, like assembling model ships.
As for the concern that reading magnifiers are bulkier than reading glasses, most are designed to fit in the palm of one's hand or pocket. Of course, you have the option of getting one with an extra wide screen, so that you can magnify nearly an entire page of text at once, and not need to move your hand much while reading.