James Packer's $1.5 billion tower should be knocked back, the City of Sydney Council's chief planner said on Thursday, arguing the private structure would "dominate and overwhelm" the long-held vision for the Barangaroo site.

Delivering a scathing critique of a process that could yet see the tower occupy key foreshore publicly owned land at Barangaroo, the City of Sydney's Graham Jahn said it was "neither necessary nor is it an obligation" that the Crown complex be allowed to make such a dramatic intrusion on the foreshore.

"There is clear failure in the assessment to consider site suitability and the broader public interest," Mr Jahn, the council's director of planning, development and transport, told the Planning Assessment Commission (PAC) on Thursday.

The PAC heard submissions about whether it should approve Crown's hotel, apartment and casino complex, as well as the changes to the concept plan needed to locate it on an foreshore site previously earmarked for a park.

City of Sydney's Liberal councillor Christine Forster praised the proposed changes as "big, bold and beautiful".

Also voicing their support were Sydney Business Chamber's Patricia Forsythe, and Margy Osmond from the Tourism Transport Forum, who spoke of the economic benefits that would flow from the "iconic" drawcard for international tourists.

But the majority of speakers opposed the plans.

"North-eastern views of the Opera House for 66 apartments and VIP guests, at the expense of permanent foreshore parkland for Sydneysiders, cannot be a defendable trade-off under the [Environmental Planning and Assessment] Act," Mr Jahn said, while nominating other sites that could host major hotels.

"There could easily be an iconic hotel facing Darling Harbour within the B4 zone without taking from the public."

Mr Jahn stressed the city was not opposed to development. He said the council had 30 hotels in different stages of development, and had recently approved a new six-star hotel at Circular Quay.

But he made a number of arguments against the Crown proposal and redesign of Barangaroo South to accommodate it. One was that the proposal required moving a planned public park away from the waterfront to the "most highly contaminated site location".

The PAC is the final decision-maker for Crown's plans as well as Lend Lease's changes to the Barangaroo South concept plan, known as Modification 8, needed to bring the hotel approved over the harbour back onshore.

Together, they account for some of the changes that would more than double the size of development across the entire Barangaroo site compared to the original 2005 design brief.

Mr Packer's complex, first put to the government as an unsolicited proposal, would increase the height of the "landmark" hotel approved in 2010 by 100 metres, and reserve almost half of its 69 floors for luxury units, in addition to its "VIP gaming facility".

Former government architect Peter Mould said no rationale had been given for adding almost 30 floors of apartments.

"The only possible explanation for this change is increased profits without any accrued public benefit," Mr Mould told the PAC. "In fact, there is considerable public disbenefit."

Member for Sydney Alex Greenwich also called for the proposal to be rejected, telling the PAC there was a strong sense in the community that planning had become ad hoc and driven by the potential for private profit.

"Following continuous approvals for increased bulk and scale, it now appears that approvals are guides that can be changed as the project proceeds and opportunities to squeeze more private gain onto the site are uncovered," Mr Greenwich said.

"Under Modification 8, public open space is relegated to an inner city pocket park."

Shaun Carter, the NSW president of the Australian Institute of Architects, criticised the Department of Planning for failing to heed the key recommendations of an independent design advisory panel appointed to assess the project.

This panel – chaired by NSW Government Architect Peter Poulet – raised a number of issues with the Crown design, and called for the bulk of the building's podium be reduced to give the public better access to a waterfront boulevard.

The department's recommendation to the PAC calls for both Crown's proposal and Modification 8 to be given the green light with only minor changes.

"What would history think of us all here today, if we chose a casino over a public park for this significant place on the harbour," said Mr Carter, who characterised the public preference for a park as a "no brainer".

Mr Carter's park remarks prompted Chris Johnson, a former government architect who now heads developer lobby group the Urban Taskforce, to quip during his own address to the PAC: "There's not going to be much of a career for architects out of that."

Mr Johnson, who was part of the jury for the original Barangaroo design competition, said the project was a "continuous evolution" from that process.

"In terms of 'planning creep', as the City calls it, the original competition brief was deliberately only a beginning," Mr Johnson said. "Indeed, the brief asked entrants if more development could be accommodated and most agreed with this."