Dont forget that cycling specific clothing does more than just insulate, it blocks wind. Having tights that breath on the back and block wind on the front is a real plus in my book. I have been out in some cold conditions and been quite comfortable. Its my hands that suffer, never my legs.

I can take warmer temps in my tights without too much issue. I have gone from lower 30s to lower 60s all in one ride with tights and been fine.