yea its not just about the density, du has better rha equivalent penetration because of the self sharpening and the flammability makes a big difference as regards to post penetration damage.
i personally cant agree with people saying the point of du is to irradiate civilian populations. i don’t think its much of a stretch to say that armies think ~30mm extra penetration or whatever is worth giving civilians birth defects, which is a world of difference from choosing it because of those effects. thats still evil, just a different, more callous type of evil.