:scratchchin: I dare say the something about them is that back then, people knew what "holiness" was, and so they didn't make everyone they drew look like delusional airheads the way they do now.
Old art is a treasure that way. There are some old statues in the little chapel I attend that are older, and they're just beautiful. The look of holiness on them definitely moves one to pious sentiments themselves. That is something the modern artists are completely lacking. I dare say it's a side effect of the N.O.. Once someone sees religion as basically a social club, something totally happy-sappy and superficial, it's no wonder they'd loose sight of those sublime qualities like holiness, dignity and virtue that used to be so evident in the old pictures and statues.
It's really a tragedy, but we've nearly lost those beautiful qualities in religious art these days. Very few can sill capture them to any degree.