I technically know why, I also know why it matters to a lot of NeoGAF because we're having a discussion here and that's fine, but I still feel compelled to ask:
Who cares?
This is freaking Nintendo we're talking about. How are you not used to this by now? How have you not come to expect this by now? How have you still not seen that the final product will rival and often surpass other hardware in terms of both beauty and performance?
I suppose it may be better to ask:
Why should I care?
I know that Nintendo uses underpowered hardware and I have for 10 years now. I know that Nintendo still makes the best, most creative, most well-designed games in the industry anyway. I know that this is going to be both a home and a portable console. I know this is going to have the combined output of their console and handheld games teams. Why should this affect any of those things?
Even if Titanfall 2 or Dark Souls 3 runs on my Switch, would I really purchase them there when I could likely find them on sale for $10 at that point for my PS4 or even more likely own them already in the first place? Probably not. Would 3rd party (particularly western) developers support Nintendo hardware even if it did match the PS4 in terms of power? Probably not. Would turning the thing into a hardware beast sell more Switch units? Probably not.
All that to say, yeah it is fine to be disappointed, but this hardly warrants some of the freak out I'm seeing. Nintendo consoles are just as strong as other consoles, their strength just lies in other places. Namely, their strong first party support, their couch multiplayer, and their creativity. It's gonna be fine.