If someone expecting their retirement age to be 67 was suddenly told with virtually no notice it had moved to 70 I’d expect them to be miffed, wouldn’t you?
To be fair, I think the golden age of an assured static state pension age - or even the perception of that - has long passed.
You barely hear anybody still working say nowadays "When I retire at 67" without adding "of course, it'll probably have gone up again by then, or even just scrapped".
State pension expectations have been dramatically lowered across the board. Most folk are much less trusting and/or much more cynical where governments are concerned - and far less willing to just accept what they were once told/believed as immutable truth.
As OldCrone said above, the only way you could make it unequivocally 'fair' and never dash anybody's expectations would be to make changes to rules that wouldn't affect anybody who had already entered the workplace; or even who had already been born.
It's a lovely idea, but totally unworkable to expect plans to be made 50-70 years in advance - by politicians who would be long retired (and quite probably dead) by the time whoever was in charge by then was allowed to implement what they'd guaranteed five to seven decades earlier.