Well interestingly, Handclaw makes the same point in his discussion of Goblin lore & practices.
Basically, he posits that "Greed" is the underlying principle to all Goblin endeavors. Goblins are, at all times/places/etc, in the search of gold, and this drives all their pursuits. (that's why I put it in front of the other 3 like I did). He says the same kinda thing you did; mech-stuff is for profit (Shredders, Zeppelins, etc), (Al)Chemistry is for profit (making potions to sell), explosives is for profit (people buy sappers?)... Etc.
<span style="font-size: 9px">(At this point, I might argue that Goblins are focused on the twin goals of "Gold and Knowledge", as I feel that more fully describes them. The explosives, the (al)chemistry... those kinda have more to do about research/knowledge/intelligence/fun. But that's just me)</span>
That being said, same is true for all races, probably. Trolls aren't just Voodoo (Mojo/Tiki/Juju?); they're Tribal and Violent and Hunters and Warriors and Spiritual and Secretive... Lots of facets. I'm just attempting to create sort of "sub-factions" out of those facets, for the Goblins.