My bicycle is never left unattended in an unsecure location, so all my stuff is always left in-place.
It is easy enough to remove + replace the headlamp and the battery pack.
On mine, the battery pack is removed every time it requires recharging. It is brought to the location where I use the included wall wart charger. The wrap around Velcro strap and cable is then easy to replace on the bicycle.
My understanding is that the manufacturer was going to increase the cable length a small amount, based on user feedback.
All of the really bright lights I've seen have detached battery packs. Yes, an integrated headlamp would be more convenient, just dimmer or less run time.