If you were wondering why the PC version of Titanfall takes up 48GB of space when the Xbox One version is a mere 17GB, the answer is audio. Speaking to Eurogamer, Respawn lead engineer Richard Baker said it all boils down to supporting the rather tame minimum specs: "We have audio we either download or install from the disc, then we uncompress it. We probably could have had audio decompress off disc but were a little worried about min spec and the fact that a two-core machine would dedicate a huge chunk of one core to just decompressing audio."
So while high end PCs and even moderate PCs could have easy handled decompressing the audio, supporting dual-core CPUs meant sacrificing hard drive space. This wasn't an issue with the Xbox One because it has built-in audio decode in the hardware itself. As a result, an insane 35GB of the 48GB install is uncompressed audio.
It would be interesting to see post-release data showing just how many people are currently playing Titanfall with a mere dual-core CPU. It would have been nice if the uncompressed audio was an optional download just for people with performance issues or something that downloads only if you deselect "audio decode" in a settings menu. I feel bad for gamers with download caps from their ISP.