Being a hardeware repair kinda guy,  this has been a
pet peeve of mine for a
 very long time.  I have run across some stuff that was designed to be easy to
 work on,  and in some cases which actually got better over time.  And while  
My favourite 2 'easy to work on' items are both video displays -- a Barco
colour monitor nad an HP1311 XY vector display. The point being there's
an extended card for the plug-in PCBs stored in a spare slot inside.
One of my least-favourite machines to work on is the DEC Rainbow. It
seems almsot impossible to set that thing up so that you can get to
testpoints on the mainboard. I can rememebr having the PSU balanced
upside-down alongside the logic board assembly, for example.
  in some cases there may be slight extra costs incurred
to add some bits,
 there are other cases where just a little bit of consideration for such
 things in the design process can make all of the difference. 
Half the time it seems things are deliberately difficult to repair. Using
heat-stakes in place of screws, putting things in the least accessible
place possible, and so on.
 "Classic" example (and yes,  it's over 10 year old :-):  I was trying to
 change out the battery in a Lumina APV.  Like a lot of other stuff,  there  
I am gettign fed up with the number of cars where it's difficult to
change the timing (camshaft) belt. I've seen many examples where the belt
goes _through_ an engine mounting, meaning you have to support the engine
and remove the mounting to change the belt. Or drop the engine a bit to
get to the crankshaft bolt, or...
-tony