When I started playing D&D back in the 1980s, gnomes were monsters: they were listed in the Monsters section of the red box rulebook, and they were described as greedy, pointy-nosed dwarves that only cared about money. So that was my first, and lasting impression of gnomes...long before there was a such thing as a 'tinker' or an 'artificer.' Gnomes were cannon-fodder, moneygrubbing little dwarves that only wanted to rob or cheat you.
That's not accurate to how gnomes are presented in the Basic Set at all.
First of all, just because something is in the monster section doesn't mean that it's intended to be a "cannon-fodder" monster to be defeated. Dwarves, elves, halflings, normal humans, mules, and traders are in there too.
Second, gnomes are listed as Lawful or Neutral, so the idea that they're out to cheat and rob people doesn't really fit. Their entry says that they love gold and gems and that they "have been known to make bad decisions just to obtain them." While it's true that stealing and cheating are probably bad decisions, phrasing things that way would be a really roundabout way to communicate that they thieve and cheat. A couple of sentences after that, Moldvay writes that goblins and kobolds attempt to steal gold from the gnomes, and in the gnoll entry right before the gnome one, he writes that those monsters "bully and steal for a living." If Moldvay had intended gnomes to be bad guys like you're suggesting, he would have said that.
What's being communicated is that gnomes don't think clearly when they have the chance to acquire gold and gems, specifically. They might agree to an unfavorable deal, make a wager without considering the odds, or something similar. (This is supported by the gnome entry in the
Rules Cyclopedia, which changes the sentence to read, "They love gold and gems and have been known to take foolish risks just to obtain them.")
Finally, the Basic Set introduced the idea of the tinker-type gnome in D&D, as Moldvay notes that gnomes "love machinery of all kinds," so it wasn't long before the existence of that archetype. It was as that archetype was introduced.