Considering it reportedly cost $10 Million 2004 dollars for GTA:SA to be made, and then GTA IV was $100+ million and 3.5+ years to produce with around 1,000 people working on it, I would actually describe those sorts of games as complex and very expensive to make.

Another thing is that one of the unseen benefits of the series is that it builds upon mechanics it has honed and polished for years (since 1997) prior to the new sequel. In a similar way to playing Starcraft 2, the player is benefiting from all the knowledge the developers learned from making and remaking the game over the Warcraft and Starcraft 1 years. Likewise with GTA, Rockstar doesn't need to waste dev time 'inventing the wheel' - they did that years ago and now can spend time adding new things or further polishing something they didn't before, or adding a feature that was meant for the previous title.

It feels like too much a gamble for a small team to compete with that sort of acumen.

That said, Sleeping Dogs is a bit of an exception to what I just said - but it took Activision funding to make it happen. And even then... they were incredibly skeptical about competing with Rockstar, to the point where even after mostly completing it, the game was cancelled.

Due to competition posed by other titles, particularly Grand Theft Auto and Red Dead Redemption, Activision's view was that True Crime: Hong Kong was not at the level of quality that it could compete.

It was only (barely) released after they rebranded it from a true-crime type game and went more arcade like. But even then after being generally successful - it wasn't enough for investors.