Most of all, the 'purpose' of a video games is entertainment, and it is the idea of 'entertainment value' that ultimately shifts units.
Still, once in a while, a creator wants to go deeper, well beyond regular gameplay to add a special layer to their narrative or game overall. A layer that may be invisible for the casual gamer, but will appeal to a chosen few who share a similar level of academic insight. These people will then gladly go on the internet, write about such things and make the rest of us think, "Ohhhh, so that's what they were aiming at... why didn't I get that?"
Because we were too concerned with the gameplay, of course.
These elements, whether they be references, nods or pure quotations, make the whole experience of playing just that little bit better. You're now a member of an exclusive club of people who know "what's really going on."
It can make you feel appreciated, alongside hopefully making your favourite games that little bit more special. All that time spent on collecting knowledge has finally paid off, and that's nice, right? And gaming is nice.
Hopefully, you'll find something nice, new and informative on this list as well.