Why not? If you jump in now and get a deck you get better, more up to date hardware, as it should be. Also with a better chip its probably up to you if you want to use that to chase higher FPS and graphics or longer battery life.
Having it as a benchmark is good, it encourages developers to aim to get good performance on a relatively underpowered device. I worry that an upgrade would muddy the waters... And drive games away from aiming for "verified" on the steam deck 1.
I haven't particularly felt mine is underpowered tbh. Obviously it's a handheld so it doesn't play the AAA graphics card melters on ultra haha. But yes, introducing a new one would affect everyone who doesn't upgrade... Plus of course the benchmark being low benefits PC players with weaker hardware, too. Budget players, in other words, who perhaps can't afford a £500+ upgraded deck. Seems a bit cold to just throw these folks under the bus.
That's the issue with bottom specced hardware. It's not future proof. It's falls out of the window of acceptable performance much faster. Look at the Horizon games. Zero Dawn plays great, Forbidden West does not.
At the bottom spec like the deck is, a two or three year refresh cadence is expected, unless they get to the point it hits in the middle of the performance window and has more leeway.
Yes, and that is exactly why having a low spec device as a common performance benchmark is useful. It extends the lifespan of low spec devices in general - at least if publishers think it's worth targeting the playerbase.
Unlikely unfortunately, they don't currently offer replacement motherboards at all.
When the ifixit repair parts initially leaked, they had a replacement motherboard available but priced at $350. Later when ifixit officially started ordering repair parts, the motherboard was no longer available.
My guess is that it wasn't worth selling the motherboard for $350 when a 64gb deck was only $400. I'd imagine the same issue would apply to an "upgrade" motherboard.