The difference between Hong Kong and the UK is geography and distance, in HK, you have one centralised department that issues all ID cards in a single location and all inhabitants of HK live within one hours travel distance to the issuing centre.
This is certainly not the case in geographically dispersed UK, indeed, given recent cuts that have reduced Passport Offices, its now virtually impossible for the UK to embark on a national ID programme, unless all data is collected via mobile offices travelling the length of the UK.
Whilst Hong Kong's ID card scheme has been running for years - my first one issued on my arrival in 1996, the movement to a digital biometric system in the early 2000's was beset by quite a few problems, and indeed what actually to store on such cards given a lack of storage space - not so much the case today.
Is it intrusive, in short, the answer is yes - you are detailed each time you leave and enter the country, and despite the fact that businesses are not supposed to request your ID details, i.e.,, you must produce your card, they seem to believe this is part and parcel of the ID system.
That said, it certainly assists in entering HK, but not in departing, you still need to queue at a desk at you exit port.