why the fetch lands?

They thin the deck, but that isn't a great arguement. They are better in decks that want to shuffle away a top deck or can manipulate the top deck.

I suggest just dropping the fetches for Mountains. I would also suggest dropping a warren for a Krenko, Mob Boss . As a one off, he is amazing.

Have you considered AEther Vial or Cavern of Souls

I ran AEther Vial in a build with Signal Pest and Adaptive Automaton so i could metalcraft Galvanic Blast but when you start mixing goblins with artifacts that's a slippery slope lol

Liked your suggestions. Also dropped a Legion Loyalist for a Spikeshot Elder since i dropped the fetches figured why not

AEther Vial is good because it lets you power out goblins past counter magic, as combat tricks. Also playing them for free is Relevant. However, it depends, cause if you want vials, you want of them and less Warrens.

Goblin Arsonist or Ember Hauler for burn and Quest for the Goblin Lord for longer games.

Krenko, Mob Boss , In the Web of War , and Raid Bombardment are very nice goblin cards.

In the Web of War costs too much and Raid Bombardment doesn't work well when there's a lot of guys that boost power in the deck like Goblin Wardriver , Goblin Bushwhacker and the 8 lords. Quest for the Goblin Lord + Krenko, Mob Boss looks like an absolute beating though. Combining two peoples suggestions. I'm a genius nbd

A great card for a goblin sideboard : Vexing Shusher