I guess it's good that they offer the option to run corded, though most guys who have a cordless rotary hammer, table saw, etc already have a fleet of batteries, and running out of power isn't a concern. I can see this coming in handy if you have a long day or forget to bring extra batteries and need to get a little extra work in, but if you're doing the type of work where you'd go through several batteries in one tool, you should likely be using a corded tool anyway.
I have a few cordless tools with the option to plug in, and I've never once considered dragging out a cord for them instead.