You have a PR problem. Tinkerer is a goofy sounding name. I don't have a replacement suggestion. That's part one.
Part two is that this class has no identity. Everyone can remember the mortar team from warcraft 3 or the dwarf gunmen, even the goblin sappers. Try to leverage that into your suggestions and ideas when presenting the class.
Part three: There is no lore to draw from in the world except for gnomes and goblins, very little from dwarfs. Gnomes and goblins aren't exactly the face of warcraft, they're sidekicks at best and realistically a pair of joke races, full of nerdy stereotypes, historically relegated to comical side quests. Neither races have ever been featured in a trailer. When people who otherwise would be receptive to your ideas hear "tinkerer", they see a goofy gnome or goblin who blows themselves up, because that's what they've been exposed to the whole game. Engineering sometimes works, sometimes you kill yourself because the parachute didn't open. *oops* hehe, funny! right?