Considering that the pc boxed version only had 1 DVD and the game is at least 30GB in size, common sense would tell most people that the biggest portion of the game is downloaded.
Optical drives in pc's are disappearing fast and optical media as a whole is a dying rapidly in favour of DD or USB installs (for OS's anyway), in fact most new pcs and laptops don't come with a DVD drive at all and some don't even have the internal bays to add one.
Bethesda AFAIK doesn't do multi-disc games, yes Bethesda goty games have 2 discs but the 2nd disc is always a one-time install and forget.
The download requirement for the physical pc version was publicly announced by Pete Hines at least a month before release, the fact that you didn't do your research before buying the game is not the fault of Bethesda.