I'm chiming back in here to clarify, for one thing, that I don't see all leggings as equal. There are some that look more like pants -- with zippers, pockets, and of course of sufficient thickness that you can't see VPL (or the lack thereof) underneath. I have some skinny jeans that I think were actually marketed as "leggings" but they fit that criteria and they're not glued-on skin-tight, so I wear them without the butt being covered. But then there are the leggings that you can almost see through, or the ones that show every contour and bump underneath them (TMI!), and those I think absolutely look much better under long tops.
I'm not a fan of the obvious leggings-as-pants look, NOT for any kind of body-type reason but because I feel like it's played out and often looks lazy. It seems to me like the modern day version of the sweatpants with Juicy across the butt. It's just something I see done every day and not done well, so personally it doesn't inspire me.
But whatever, I think people should wear whatever they please, and I don't want anyone to dress to please me! It's just not a look that I will ever seek to emulate, even if I thought I looked cute enough in my running leggings to wear them all day long to knock around town.