Pretty much this.SirBryghtside said:90% of physical copies come with DRM nowadays anyway, so you're effectively just buying the digital copy anyway - with all the disadvantages that carries. I like buying physical, but when the price online is so low for exactly the same product, it's hard to logically reason against it.
That said, if I have a choice between Steam and a DRM-less site like Good Old Games, I'll go for GoG every time.
But really a lot of the time it just comes down to 2 things for me buying the physical.
1) Is it a collectors edition or something like that which comes with some really neat extra stuff? An example for me would be Skyrim (I sadly didn't get one of those), the Alduin statue looked good and I'm really into maps (which is why I'm considering getting The Elder Scrolls Anthology physical copy).
2) Is the game really big space-wise? If the answer is yes, then I will more than likely get the physical copy as I have rather slow internet (256 kb/s download). So if I was to play something like Titanfall then I would absolutely get the physical as that would take me days to download. With the physical I only have to worry about updates. So anything above about 15GB and I will get the physical. It is just more practical for me.