It is difficult to get a loose joints sex doll to pose or stand. Even if you’re not interested in taking photos and so on, dressing a loose-jointed doll is a pain in the arse unless your lady stays nude. Such a doll will flop all over the place and is unlikely to hold a ‘doggy’ position. Stiffer joints definitely offer more variety in posing for “playtime.”
Another thing to consider is moving or carrying your love doll. Inevitably you will want to move her to change the sheets or give her a good clean. Carrying a loose-jointed doll is much harder than a stiffer jointed one!
The weight of the doll is a killer when the joints are loose. Some tight-jointed dolls occasionally have REALLY stiff joints, but the resistance is just enough to be more realistic when putting them in position for whatever you want.