Go weigh an Irbis titanium screw and then a BD Express 17 cm, which is the closest equivalent. The Ti weighs almost exactly half what the BD weighs. That's why people take them.
Yes, they place easily in glacial ice, but they are harder to place in water ice.
The small threads are the reason why I place them 90 degrees to the slope, whereas the Express should be tilted at 15 degrees down from the perpendicular. The smaller threads mean also they melt out faster.
So they have their place as long as one knows their limitations.