I assume the chief reasoning behind this decision twofold. First, it's a crapshoot to get alternative stores working on my steam deck (I wouldn't expect my less technical gamer friends to feel confident installing a game from Epic/EA/Ubisoft). It's also a financial decision, as Valve presumably isn't charging the OEMs a licensing fee.
In a market that's getting more crowded by the day, where so many of their competitors are using the same SoC and come in at roughly the same price point, it's a rational decision to control costs as much as possible. Not to mention, they also need to compete against the Deck itself, which Valve is subsidizing to hit its pricepoint. The alternative would be to innovate and differentiate your product offering from your competitors (like the original Legion Go, which had detachable controllers and a fancy pseudo-mouse). The fact that this machine didn't carry those features forward is a strong signal that the bottom of the market is where the early wins will be.
Keep in mind also that Microsoft is planning their own handheld xbox experience. Speculation: MS' effort will look a lot like Valve's, with Xbox games coming day-and-date to OEM-built handhelds, as well as a first party reference implementation that's intended as a benchmark for devs. I imagine that most OEMs are using the cheaper steamOS pricing as a hedge against future gouging from MS; if there's an "Xbox certification process" that proves to be too cumbersome, a vendor that's already shipping cheap(er) devices en masse with SteamOS has the option of simply dropping windows support altogether.
In a market that's getting more crowded by the day, where so many of their competitors are using the same SoC and come in at roughly the same price point, it's a rational decision to control costs as much as possible. Not to mention, they also need to compete against the Deck itself, which Valve is subsidizing to hit its pricepoint. The alternative would be to innovate and differentiate your product offering from your competitors (like the original Legion Go, which had detachable controllers and a fancy pseudo-mouse). The fact that this machine didn't carry those features forward is a strong signal that the bottom of the market is where the early wins will be.
Keep in mind also that Microsoft is planning their own handheld xbox experience. Speculation: MS' effort will look a lot like Valve's, with Xbox games coming day-and-date to OEM-built handhelds, as well as a first party reference implementation that's intended as a benchmark for devs. I imagine that most OEMs are using the cheaper steamOS pricing as a hedge against future gouging from MS; if there's an "Xbox certification process" that proves to be too cumbersome, a vendor that's already shipping cheap(er) devices en masse with SteamOS has the option of simply dropping windows support altogether.