Moving to a new stadium has to make financial sense.
£100m might sound cheap but it is £100m we don't have.
For it to make economic sense we need to generate £100m in either additional sales or savings over Goodison Park over the lifetime of the project.
£100m is likely to cost around £7m per year in borrowing costs.
Goodison currently generates circa £20m so a new stadium would have to a 50% rise in gate receipts to reach break even point on the borrowing costs alone (effectively we'd have to increase crowds and box use at the same time as increasing prices)
A football only stadium in somewhere like Walton Hall Park would be an economic disaster for the club. Any new stadium project needs to be in the city/docks and be used every day of the year.