The older bricks that were made back in the day, "pre-2K", seemed to be made out of a harder more durable brick that seemed to hurt your feet when you walked on them. Now it seems that since the other brother of the LEGO family took over, things have changed and you are seeing tons of themed sets coming out which is awesome, but at the same time the plastic seems to have changed to a softer mixture of plastic.
Most AFOL's think that this is Due to the fact that the bricks are now being made in China, compared to when they used to be made in Mexico.
If you compare a Medieval sword or pirate sword made during 1995 time and compared it to the new stuff. You will notice that even the color of it is different. the old Medieval swords were bright and shiny and hard as a rock. The old pirate swords you could even pick your teeth with them like a tooth pick. Now they both seem to be made out of an entirely different plastic and bend just by pressing on them with no effort.
Most would argue that this is what is killing off the AFOL'S sales with in the U.S., others would argue with the new rules on Ebay and Amazon selling put into place by the Obama administration with the next tax code on selling things would be the reason. I personally have not spent more than $200 last year down from $2000 the prior year. The only reason I bought anything at all was the new Friends sets. I loved LEGO until they took out the main reason I was buying their toys. I bought their toys for their durability aspect. It was one of the only toys on the market that didn't turn to profit and become mass produced in CHINA, now I will have to start buying Playmobil.