How many more justifactions do you want to have given yourself in your own question? They stop chafing (which apparently only has one f!!), they are comfortable and they keep you warm so whats your issue?!
I wear cycling shorts (under normal shorts) in summer and tights in winter - just get a long T shirt that hangs over them a bit more, or better still a jacket that hangs over..... personally I think that looks pretty cool on runners that i've passed in the street! But i'm one more for not wearing shorts over them, that just looks crap!
I've got a pair of tracksters too but they are just wrong in so many ways that I don't wear them!
p.s I remember the first time someone commented about my tights, they told me I looked like Billy Elliot - but who cares, I still wear mine!!