Hair is important, otherwise you're bald. I think facial hair wasn't commonly rendered on many characters prior to the 7th gen because the hardware couldn't realistically make it real, but the 7th gen popularized it and made it revevant to gaming. The Witcher takes it to whole new level by making Geralt's facial hair grow in real time because the hardware made it possible, and it's nyaxt gen. It's the little things people!

"The beard grows as time passes and when Geralt moves between locations," he toldEurogamer. "The beard has several 'states' and these states determine its length--the longest is really long but it's not Gandalf-long."

"When you download the free Beard and Hairstyle DLC the growth of the beard will stop because we decided that when players want a predefined look, it would be weird to require from them to reapply it time after time," 

DLCS are good, in theory. But lately the concept has been abused by AAA publishers and it became a controversial subject ever since. Does this mean The Witcher is now an empirically bad game even though CD Projekt promised free DLC and explicitly said they won't charge for anything unless it was huge? 

http://www.gamespot.com/articles/dynamic-beard-growth-confirmed-for-witcher-3/1100-6426116/

So by the end of the game he'll look like this?

Yes, we start as Geralt and end as Gandalf

Edit: Apparently no Gandalf. I'm sad now.

That's shorter than Gandalf's because he hasn't been growing it ever since he was a fetus. So probably yes.

Edit: I've read the qoute on the OP for the first. It's vague, but I still think it can be that long. 
"the longest is really long but it's not Gandalf-long."

Ladies and gentlemen: diminishing returns.

Why Gerald brought two sword with him is because one of the sword is to cut his beard...........make sense.

...A facial hair model swap...yay? I'm pretty sure there are mods that do this kinda stuff in multiple other games like Skyrim :P