This thread is yet another nice demonstration that critical thinking is something that is lost on most people in this community. Or maybe it's just that people are more interested in pushing certain narratives as soon as an opportunity arises, no matter how flawed a presented premise is. Now listen:
The type of games that were defined as selling well by the OP's guidelines is the same as the one that accounts for the vast majority of studio closures over the course of the last ten years. This means that that type of game is currently the most successful and least successful at the same time. Why is that? Because they are the most produced games by far. If you compile lists of AAA and A games (development and marketing budget is what matters here), then you'll find that non-colorful (as defined by the OP) games account for more than 80% of all titles. So at the end of the day there are more non-colorful games that succeed, because there are multiple times more of them than colorful games. At the same time non-colorful games are more numerous when it comes to flops too.
But instead of looking at the big picture, people are focusing only on the top end when it comes to sales. Naturally, the conclusions drawn from that are bound to be flawed, because large pieces of data are being omitted deliberately. The actual answer to this thread is as simple as "Games that do not exist cannot sell.", hence why successful colorful (as defined by the OP) games are in the minority in today's market.