I regard the postal service as a public service (i.e. should be funded out of taxes) because over the last 150 years it has become the one guaranteed way that people can be contacted - I'm thinking not just Christmas cards or Boden catalogues, but gas bills, bank statements, doctors' letters reminding of appointments etc.
Of course there are other ways of contacting people, but not everyone (esp. older people) has access to email.
You may disagree with my concept of a service - this is my opinion, not a fact.
On profits, I believe RM has suffered because some more profitable parts of the business (e.g. Parcel Force) were privatised years ago.
On pensions, my understanding is that a few years ago the pension pot was thriving so the government (it IS the govt. ultimately - RM is nationalised, so no private shareholders involved) took a 'pension holiday', i.e. froze their contributions to pensions. Unfortunately, this 'pension holiday' lasted several years and coincided with a fall in stock market so that the pension pot is now very far from thriving.
This has obvious implications for RM workers who have been paying into pension schemes for many years in good faith, believing that their contributions were being matched by their employer (the govt., ultimately).
Again, this is my understanding of the situation, gleaned from media reports over the years; I can't quote you chapter and verse on sources, so I stand to be corrected.
On the late delivery/lack of Sunday collection/lack of second post Mon-Fri - these were decisions taken by RM management in the drive to be profitable, NOT in response to grumbles from the workforce.