[Brightcolours]

• Why all those buttons?
  

Because there are so many parameters to control. Less buttons means less parameters means less control.

However, try the Canon DSLRs with touchscreen. They have touchscreen done "right", and you don't "need" the buttons anymore. 

• Cameras are beeping, but why can't I tell them what I want?
  

Speech recognition is an odd way to control things. Others can hear you. It is slow.

• Why do  I have to turn the camera from landscape to portrait instead of turning only the sensor?
  

Turning the camera is fast and intuitive (unless when on tripod)... Turning the sensor is yet another control button?

• Why is there no camera able doing the focus adjustment with their own LiveView?
  

Because cameras can't know the exact behavior of the lens motor and electronics. Cameras don't know step sizes.

• Do we still need tripod screws instead a quick mount, or maybe both?
  
• Why is WLAN and wireless LiveView such a big deal these days?
  

Remote view finder is handy at times. Just like swivel LCD displays are handy at times. Having a remote trigger + live view just is a nice tool.

• Why is nobody doing a removable display?
  

Why would you want to remove the display?

• Why is no camera manufacturer able to do focus stacking for macro right in the cam?
  

Because AF is not that controllable (every lens behaves differently). I can see how one would design a dedicated lens for a certain body for that, though, where the photographer tells the camera the step distance between shots.

• How difficult is it to focus on two different distances and the camera calculates it's DoF (I know, DoF is more or less an illusion...)?
  
• How about somebody manufactured a sensor for all the old and good analogue bodies?
  

Has been tried twice. Problem: one does not just need a sensor (doable), but also battery, memory, computer, controls (problematic). And nowadays, what would it add to the DSLR landscape?

• Or make the sensors interchangeable? I would like to have a Foveon in my Nikon  B) for landscape, or a high ISO type for lowlight. Of course, I can buy myself into coma with bodies, but the I expect them to walk for themselves and not being carried by my poor back...  :wacko:
  

One or two manufacturers actually are researching into that area.