People play up the whole "look how China's changed" number, saying that "they've come a long way since the 1960s", perhaps ignoring that the administrative role of the colonial gummint too had evolved over time. Nobody expects the post '80s generation to have a clue about what life was like in Hong Kong during the first half and the third quarter of 20th century, beyond boring textbooks and the ramblings of disgruntled seniors (who, what, swam over from across the border with only their shirts on their backs?). It's safe to say that, by then at least, the era of plundering and oppression (?!), and whatever else you want to accuse the colonials of, was long gone.
Therefore, it stands to reason that when the young'uns wave their colonial flags, it isn't because they agree that dogs and the Chinese should be banned from private clubs and certain public areas, or that they agree with the business of "soaking up riches (stained with the blood and sweat of industrious Hong Kongers) from the fragrant harbour and washing them down the Thames."
What they know is what they witnessed in the years leading up to the handover - that is what they remember and yearn for - a free press, a swift movement towards full representation in the gummint that is compassionate to their cause (and, obviously, one that sticks it to the commies), and an end to cronyism. Look at the root cause. The way things have panned out over the past 15 years, can you really blame them? They're getting tired of seeing the city's administrators kowtowing to the Central Gummint Liaison office and the leaders in Beijing.
I agree that integration with the mainland is critical to Hong Kong's survival, not because it is true in and of itself, but because it is how the Communist overlords want it. It has its benefits, on many, many levels, but I call BS on the notion that it is truly needed for Hong Kong's survival to the extent that it is being proposed. Au contraire, over-reliance on the mainland economy will enslave Hong Kongers. The city's administrator's should never permit that, for it will be the greatest let down of a people by their gummint.