But do you have actual numbers to back those claim? Because running a store like Steam is costing a lot of money. Of course, Valve is not to complain and I agree that they could reduce the 30%, still they are the best right now.
Steam also allows publishers to generate keys for free, and by doing so they take a 0% cut. Meaning you can host a website to sell your game with generated Steam keys without giving Valve any money. Also Steam is offering you tons of services when you are a dev and they will always try to do the best they can to accommodate you. Like Steam save clouds, or just the store page. If you are doing it by yourself it cost money, they also host your files, the bandwidth to download games is not free. Remote play, family sharing etc etc... Tons of services. And 30% is the basic %, after a certain number of copies sold, the percentage reduces little by little (I no longer have the exact numbers in mind but it can be found on the internet)
And of course I would love to see a Portal 3, or a Team Fortress 3, or Half Life 3 but it is what it is. At least we know that when Valve is releasing a game, it's gonna be a masterpiece. And they tried to do HL3, they just didn't found a good story to justify it so they abandoned the project. I'd rather see this than IP's being milked to death. It's not because they don't release games often that they don't inject money.