I think the answer to this is the city should do all the land acquisition/architecture/engineering/environmental impact research/planning approval, and then off

I think the answer to this is the city should do all the land acquisition/architecture/engineering/environmental impact research/planning approval, and then offer that completed package for developers to bid on. This will make it much easier for developers to build projects as they'll not have to worry about paying these up-front costs only to have the city reject their proposals, while still allowing voters to ensure truly terrible projects aren't built. Surely there must be downsides to this approach, what are they?