Of course any modification like this can be done if you are willing to pay the money, and in theory it would be a good idea. But I would argue that it is a little overkill. Oil pumps can fully circulate the oil throughout your engine within a few of seconds of startup. Modern lighter weight synthetic oils also help a lot with this. Also keep in mind that the parts are still not completely dry on your average cold start; they still have a thin film of oil that should do the job for the 2 seconds it takes for everything to get properly lubricated. Well made vehicles can still last a really long time without any oil system upgrades. The million mile Tundra's are proof 🙂
Because it would cost too much and the car manufacturers want the vehicle to wear out ten minutes after the warranty expires so they can sell you a new vehicle.
There are add-on aftermarket pre-start oiling systems available. Some use electric pumps, some use a pressurized oil accumulator.
https://www.youtube.com/watch?v=vyaGoj60A6s