They cut down the board years ago for Lite models, but I guess now it's actually economically viable to do it large-scale. The cost of adding in a spare shell is trivial in comparison, but it's good to see that they're making a solution that appeals to everyone (who likes their DS Lite dust covers in black).
I am a bit concerned about the battery switch-up, though; easily replaceable is great, and the CR1220 is gonna be a lot easier to fit into a Lite shell, but it's also got a quarter of the capacity of a 2025 at best. Even with a reduction in power consumption, you'd probably end up swapping it out semi-regularly.