You might think this is the natural evolution and it is to be expected as common knowledge that people tear old structures down to build bulkier products.
Not so correct. Zoning and land use dictate the type of products that get built there. For example one can?t buy several side by side houses on large lots in El Camino to tear down and replace them with an apartment. The zoning dedication prohibits construction of a drastically different type and size of homes.
Surplus of land never meant cheaper prices for home. However the home amenities are better typically in this scenario such as having a driveway, a courtyard, bigger rear yard, wider side yard, a third car garage, and more single story products. City of Irvine still enforces planning standards even for the scarcity of remaining land. Fortunately like a creative attorney one could still have met the laws and gets away with murder. The new and denser products must still meet the old planning standards through creative interpretation and not violating the life and safety of building safety and fire codes.
Irvine planning standard has never insisted on detached homes having a driveway and a big backyard. However, guest parking standard has always been stringent. Each home must have guest parking within a short walking distance to the front door. When land was plentiful it was assumed the the only way to have met the code was to have guests park on the driveway. Very few curb then was long enough for a series of parked cars so the only solution was driveway.
Because of these excessive driveway curb cuts the invention of one driveway for every 4,6,8 or 10 homes has been more land efficient so the guest parking count could be met on the longer uninterrupted curbs. Since the planning code never stated the guest parking must be dedicated to the exclusive use for each home as long the reasonable walking distance is met made it possible for homes to have no driveway. Planners do validate that there is guest parking for every home within a 150? walk (defined as a reasonable walking distance many decades later as detached condos began to challenge old rules)
When land starts to run out city could not just change the existing zoning to accommodate bigger and denser products simply like you said. Tearing down a house and replace it with an apartment, buy out buildings and replace them with townhouses or condos.
Zoning change must be on a ballot supported by over 6,000 pages of EIR then must be approved by the general population and before getting it on the ballot the zoning modification has to be approved through planning commission then city counsel and always shot down by NIMBYs.
Zoning modification is no different than the Veteran cemetery and how long has this taken?