I have have computers for more than 20 years now and NEVER had a case of failed ram. I had a Thinkpad that need to replace the... logic board :P They were covered by the 3 year warranty, so I did not pay anything. Also had a HP that needed logic board replacement. Never had problems with desktops.
Witch brings me to my next point: they have warranty, If you are worried about it, buy extended warranty.
The only way to make smaller and lighter notebooks is this, why carry 500g more all day just for the chance to upgrade your ram or pay less in case of a failure out of warranty? Everyone is complaining but it doesn´t make any sense. Buy heavier and larger notebooks them!