... Why does destroying it give you 50 gold? What will you buy? How does 50 gold help your stats?

Noticed this a while ago, but seriously what's the reason for this?

I believe all buildings of a certain type are worth an X amount of gold. E.g. Towers are all worth 150 gold, all 'inhibitor' like buildings (Nexus, inhibitor) are worth 50 gold. Hence, when you kill any of those kind of buildings, you gain 50 gold. Since it isn't really a big deal, they never bothered removing the 50 gold gained from the Nexus kill.

It's great for building that 'total gold earned' stat. Which I treasure more than children.

Riot enjoys doing silly things that change nothing. Like all the hidden passives

I think its awesome. I'm like yay I last hit the nexus wat up *****es lol.