It may be impractical enforcing customers to use only wired input devices such as keyboard and mouse. For example, it makes difficult to place computer case in a safe.
Microsoft makes OS more and more secure so off-line attacks might rise. Bluetooth allows to connect only paired devices (while wired may be disabled by polices).
Also, for example, one (why not Microsoft?) may develop a service that pings administrator's cellphone and auto locks system when out of range.
There may be more valuable applications invented in the future. It is unclear why this feature is removed. This is widely discussed in the web but I was able to find only one (closed) issue on this Connect.