Quite a few different reasons to be honest.
For now, they are quite expensive processes however, I think in time it will be refined and become a cheaper all-round alternative to farming pigs, cows, deer, ducks, chicken, etc. You can include all dairy and seafood products as well.
The amount of land required to produce products will be significantly reduced and should have a smaller carbon footprint if you consider the entire process of traditional livestock farming. Obviously, there will still be farming required for the plant-based resources that are required to make lab-grown meat and dairy goods, though they generally require less space and have a lower carbon footprint.
This aspect is already being tackled with research into vertical and indoor farming where crops are grown indoors in vertical stacks inside old converted warehouses. This area also has plenty of growth potential though the process is still expensive as well. It has the benefit of optimal growing conditions that aren’t affected by weather, insects, pesticides, etc.
