Another thing I hate about a lot of recent camera hardware is the move toward cheap plastic, everywhere. I shoot pretty much only with old manual-focus lenses from days of yore. Most of my lenses are older than I am. They're all made of metal, built like a tank, and way easier to use. No fidgety UIs or menus to manipulate, perfectly calibrated infinity focus (slap the focus ring to the end until it stops and landscap…
A nikon D3/D4/D5 will withstand a huge amount of abuse - at least as much as my more obviously metal pre-digital SLRs did. Another issue to be aware of is when using large, heavy lenses, a lot of stress gets put on the mount point and that most modern pro-orientated DSLRs are actually stronger than their old film equivalents in this regard, as the engineering has improved over time.
Re: arca-swiss plates - the reason camera companies don't do this is because of the licensing fee (source: I've talked to a bunch of them, and this is always their reply). I'm sure Thom is aware of this, but the licensing fee is not insignificant, and with extreme pressure to control costs it's not surprising that companies very rarely do this. Of course I personally would be very happy to see them included, but I know there are a bunch of people that don't use them, and would resent the extra cost to include them.