The makers of Poser really don't have anything to do with how clothes fit either. It's the clothing creator's skill that determines how well clothing fits.

Clothing 'out of the box' should fit Victoria 4. If it doesn't you should return it and get your money back, or if it's a freebie throw it away. I honestly don't understand why so many people have trouble fitting clothing to V4. The only thing I can think is if they are turning dials on V4 that aren't matched in the clothing. And that, once again, is because of the clothing creator. Personally, I don't match every single morph, only the FBM ones, as to match every single morph would take a ridiculous amount of time and I'd have to raise my prices to cover the extra work put in.