I wonder what issues, Western countries are blundering into currently in that regard.
To follow-up on it a bit, whenever Western countries are put into a situation like that, they're effectively forced to do exactly what happened here. After all, whether or not something becomes public or not is completely outside of both parties' control. The minute some newspaper-person looked up the terms on the treaty and published it, there would have been an immediate international confrontation. So Britain was forced to come up with some kind of framework whether they wanted to or not -- simply to prevent random crises in the future.
1. anecdotes from exasperated civil servants who were not party to the state level discussions,
or 2. declassified documents about the discussions.
Additionally, TFA notes that China had HK and Macau removed from the "non sovereign territories" UN list years earlier, so that both couldn't aspire to independence.
Considering that HK was lost following the Opium Wars and the first of the "unequal treaties", something that was considered a deeply humiliating episode in China's history, it's not surprising that their government wanted to "right that wrong".
Thatcher was simply delusional about her initial plans ("I really don't understand why they don't want to renew with us this thing they call Unequal Treaty?")
edit: for example the chinese did nothing to stem the tide of people to-ing and fro-ing when HK was still a colony, I recall some squaddies complaining bitterly about having to shoot at them up the hillside whilst People's Army looked on bemused.