We (as in humanity) can continue to develop both EEG caps and direct implants. The technology is young and there's no telling what side benefits and additional functionality either one can have.
And the implant, much like early EEG devices, barely works for now. Imagine what they'll be capable of 10-20 years down the line.
Because brain activity doesn't stop when I'm sleeping, it's more like the brain is just idling.
If we wanna go with computer terms, sleeping isn't shutdown. Sleeping is sitting on the desktop with no active windows. All the background processes don't stop when you're just sitting there and admiring your sick wallpaper.