I'd gladly agree to pay more in exchange for a legally binding agreement that higher prices mean video games free of predatory monetization and reasonable pay and job security for the people making the games. But we both know that they have no intention of doing the right thing, no matter how high the box price. They're already raking in record profits while laying off huge chunks of their workforce and giving the c-suite ever-increasing annual bonuses.
They've perpetuated the lie that microtransactions were a necessity and the $60 price was unsustainable for such a long time that people actually believe it. Now they want to increase the box price while keeping the predatory monetization, having their cake and eating it too.
The Series S is very frequently on sale for $50 off, sometimes more, and often comes with a bundled controller or game.
The Deck is only playable in Act 1. The frame rate in other acts struggles to reach 20 FPS, even on low settings. Also, the $400 deck you're referencing cannot even install the game unless you buy an accompanying microSD (which I can't imagine provides a good BG3 experience) or an SSD which you then crack open the steam deck to install (which will be too intimidating to most casual, non-tech people).
$450+ is a more accurate price point for playing BG3 on Steam Deck; 50% more than the Xbox MSRP, which is significantly discounted every few weeks. The Xbox will also offer a much more convenient experience to those who want to play the game on their TVs, and the game will look nicer on that hardware.
The Deck is an awesome little device, but you're overselling it here, and ignoring a lot of nuance.