This is mostly relevant for keyboards, but might be critical for mouse users too.
The user should have control over if they want the keyboard/mouse always stay on or if it should be in soft-sleep mode.
Especially after a very short time (sometimes seconds) the device enters a soft-sleep mode and becomes non-responsive. When typing a password or editing a document the first letters or words are not registered. This is critical for data entry, coding, multitasking and similar tasks.