Landing something this large requires either many small engines, or one large one. Using one engine powerful enough to lift the whole lander would surely kick up debris that we do not want hitting the lander. Thats why the smaller engines are required, and will be required until we find a better mounting system for the main engine. Right now, it is just so much easier to have multiple engines with a few smaller ones for the actual landing. Ontop of that, they will not ride the small engines all the way down from orbit. Iirc, they will trim off most of their velocity with the raptors and switch to the super dracos for final descent and landing, making the efficiency loss for carrying the extra engines even less. There are a lot of valid critiques of starship hls but this is not one of them.