In fact, many in Catholic Londonderry were openly pleased when Collett, aged 37, died in Altnagelvin hospital last Sunday.
On the previous Tuesday at around 8pm, an IRA unit used a sledgehammer to smash a way into his home in the Shantallow Estate on the northern edge of the city. Collett was seized, forced to lie on the ground and then shot at point-blank range in the back of both knees with a .38 magnum.
With the bones, tendons, muscles and arteries of both legs shattered, he crawled to the front door, gushing blood and screaming and hammering for help. By the time neighbours were alerted and an ambulance summoned, he was almost drained of blood. He died five days later.
In a statement admitting the shooting, the IRA accused Collett of having sexually abused a large number of young children on the nearby Carnhill Estate. This was true. Over a period of at least a year, Collett also abused members of his own family.
Most of his victims were girls, at least one as young as seven. On one occasion Collett raped a girl while a 13-year-old boy watched, and then urged the boy to rape her.
The boy is now in the care of social services, both for assessment and treatment and also for his own safety.
Almost all the children came from the square in Carnhill where the Collett children lived with their mother and her partner - she left Collett nine years ago after suffering numerous serious physical assaults by him as well as extreme mental pressure. However, Collett frequently visited his children in Carnhill.
Many of the families living on the square are distraught and have asked the Northern Ireland Housing Executive to transfer them to other areas. Others are demanding that Mrs Collett and her family move out, saying that their presence is a constant reminder of the damaging ordeal suffered by local children, some of whom are showing behavioural disorder and are being treated by the psychiatric services.
Support for the IRA action is widespread in Catholic areas, where Collett is spoken of as a sordid and malignant presence whose removal from the community, no matter by what means, is seen as wholly welcome. He became involved in terrorism through membership of the Irish National Liberation Army (INLA) in the Eighties and served two-and-a-half years in prison on terrorism charges; he also received a suspended sentence for 'flashing' at children in 1982.
Collett's wife stood by him in 1982, when he agreed to undergo a programme of psychiatric treatment at Gransha mental hospital. She was already aware of his disturbed, violent nature. He had begun beating her up within six months of their marriage in 1977. She hoped that the medical treatment ordered by the court might 'straighten him out'. However, he dropped out of the programme after a month. There appears to have been no monitoring of his progress, or lack of it, by any agency of the court.
Their marriage effectively ended at that point, although the couple stayed together until late in 1983 when, after a particularly savage beating which left her in hospital with a fractured skull, Mrs Collett walked out, taking her three children. She obtained a formal separation in February 1984.
Now in her mid-thirties, she comes across as a remarkable woman, forthright and articulate and handling her situation with great courage and poise. She recognises that many of the families around her live in constant horror of what has happened to them.
She is hurt that she has lost her part-time job in a city-centre restaurant following phone calls protesting at her employment. She believes, as do others in the area, that her ex-husband had to be punished. But she does not think that the IRA had the right to do what they did, or that her home should be the focus of hatred.
The case first came to light in October, when the mother of one of the child victims approached Mrs Collett. The RUC and social services launched an investigation and the full extent of the abuse began to emerge.
The story became public at the beginning of this month when, with rumours already abounding, several people approached the Derry Journal, which led its 4 December edition with the headline 'RUC probe Carnhill sex abuse'. At the same time, Sinn Fein's office in the nearby Racecourse Road was 'inundated' with demands that something direct and drastic be done.
There were explicit demands for IRA action, equally explicitly rejected by senior republican figures in the area. The republican movement became central to the case because of the problem involved in policing areas like Carnhill and Shantallow. Voting figures suggest that the majority of people here are in the SDLP not the Sinn Fein camp. But since there is, effectively, no support at all for the RUC, even some SDLP supporters tend to look to the IRA when they want direct action against local criminality.
Given the fervour with which local people were demanding action, particularly as the flurry of statements being taken from local children began to reveal the horrifying role played by John Collett, it is fair to say that the republican movement might have lost support in the area had its armed wing not exacted retribution.
In many respects, cases like Collett's are tailor-made for the Provos, widespread horror and fear translating into acceptance of the IRA as enforcer of a communal morality. This has obvious attractions to the organisation, particularly if its violent tactics to advance the nationalist cause generally are being called into question.
In cases such as this, the IRA's base of support is broadened and its readiness to handle such morally charged issues - the targeting of drug dealers comes into the same category - while striking many as opportunism, is seen by Republicans as common political sense.
More generally, the savage satisfaction in the locality at the maiming and death of Collett reflects the brutalising effect of almost a quarter-century of violence.
Collett was one of 13 children, of whom two died in infancy, born in Springtown Camp, a scatter of disused corrugated tin huts on the outskirts of Londonderry which had been abandoned by US forces at the end of the Second World War and then squatted by families from the Bogside who had been denied homes because they were Catholics.
He spent his formative years in poverty and in appallingly crowded conditions - the hut had two makeshift bedrooms. As a child he was severely abused physically and quite possibly - because it was a common occurrence - sexually as well.
If there is a fragment of hope anywhere amid the debris, it lies in those like Mrs Collett who manage somehow to transcend their own suffering, to feel for everybody and blame nobody, and to believe in a better day coming. 'Everybody in this story is a victim,' she said.