Why lab meat? Plants are right here now, require very little electricity, the sun is free, they can't run away, many can be eaten with very little preparation. It's both cheap and easy.
Various plants (dark leafy greens/cruciferous vegetables) do make up the foundation of a healthy diet, but do not provide significant protein or fats. Meat is very useful from a dietary perspective. You can make a quality vegan/vegetarian diet, but hitting high protein goals for those who are active can be difficult. The majority of vegetarian+ protein options are also high in carbs.
Plus, meat is tasty. It makes perfect sense people look forward to lab-grown variants that are ethically sourced and have no adverse health effects.
They don’t taste the same though
can't run away, fantastic
Because not everyone shares your preference and/or discipline for plants. Lab grown meat doesn't require a planetary scale realignment of moral values and habits.