I get why Amazon wants to/has to make their own video content: People expect it these days and they have to compete with Netflix and HBO. But in gaming, there are already a ton of publishers and a ton more developers in all shapes and sizes and for all markets and kinds of games.
It is a great time to be a PC gamer. There's so much choice. If you don't think there is, try playing something new instead of the same old things.
Anyway, there are a lot of people making games. Some great, some good, some bad. What is Amazon going to bring to this that isn't already being done? It's not like the video service where they have to meet expectations, and it's not an unmet need since there already are tons of games.
Amazon is hiring some heavy hitters and spending A-level cash on game engines. This says they intend to bring out an epic franchise brand, which means they will have to spend a LOT on making it, and take years, and after all the work, maybe people won't want to play it. Most games end up like that, especially the big, grand, spendy grand attempts. Very few of those command lasting presence. So they're basically betting a lot on what will probably be ONE title and the odds are it won't be huge hit. Maybe a moderate hit. Why do this? Why take on that financial risk when there are plenty of existing companies and people who already do that?
Amazon already sells their games, and now they have Twitch to show them off too. Amazon doesn't need to make content in this space.