The “unfinished” ceilings are common in warehouse stores. It is largely a feature of practicality. Since electrical, water and ventilation typical run overhead and needs to be serviced occasionally, putting drop ceiling tiles up would make them difficult to work with, particularly when you need a scissor lift (rather than a ladder) to reach the utility lines. But it also has some benefits like higher lighting fixtures which means less direct/more ambient lighting, fewer places for pests to roam in the building or dust to build up, etc. It may just be that I’m used to it, but it doesn’t bother me as an aesthetic. Drop ceiling is more common in smaller stores.

Not sure what you mean by the drab colors. The floor looks like it could be whiter and probably needs a polish, but the blues look nice enough to me. There’s not much to decorate though as most of the story is wide open with very few surfaces that aren’t covered in products for sale.