I have to agree and I did think this when I bought the keyboard a few weeks ago, as at no point will it be used as wired. The battery will need to be replaced at some point, and at £120 for a wireless keyboard, I expect to get about 3-4 years out of it. Batteries also diminish in their capacity over time.
I used a K800 for 4 years, a great keyboard and weeks between charging, but you can tell the difference alone when ALT+TAB with the K63 wireless as It's instant, like wired, unlike the K800 where there's a slight delay, which in gaming, especially FPS is critical. I love this keyboard though, It's well built and solid, instant responsiveness, the tenkeyless is great as I don't use numpad anyway, but I would liked to have seen some RGB. Hopefully the battery can be replaced in the future when needed.