Here is one of bitcoins major flaws.. NO method of identifying and replacing lost coins which is unstable and potentially inflationary.
Yes... one of the biggest flaws. We assume that the number of Bitcoins in circulation will slowly increase from 2009 to 2140 and that they will stabilize by 2140. If such large numbers of BTCs are "lost", then the currency will be extremely vulnerable to deflation.
Something should be done to maintain the total number of BTCs available.