Actually, many studies have shown that the correct use of lower case (with capitalization as appropriate) is much easier to read than all caps.
Some people who use all caps harken back to the old wire service/teletype machines that weren't capable of anything else. In my earliest radio days all the wire copy from AP and UPI printed all caps and I always found it more difficult to read on the air than standard text. I'd rewrite the stories whenever possible anyway, and I always did that in standard form (on typewriters, remember those?).