Personally I don't think the issue is "3D fitting" - the issue is that the sizing and fit of clothes hasn't both been: standardized and quantified. Do both and a 3D fitting room wouldn't be necessary to begin with.
Body types vary widely though. If you’re athletic you may have a strong shoulder to hip drop, getting shirts that are blousy in the midsection. Conversely, if you’re heavy set or short you may get garments that are overly long. Some companies do try to address this to a degree with slim or athletic cuts, and yes a tailor could take you the rest of the way ‘mostly’ there, but the future of clothing is 3D scanning and…
I also think what you’re describing could be easily solved with more measurements of clothing you’re considering.