It is difficult to argue with the diversification of the ETFs and I by no means avoid them, but given that most are market-cap weighted, they skew toward large stocks and self-perpetuate the growth of a handful of large cap stocks. So every $ invested in VOO, has 4.2% in APPL. I'm not sure what impact that would have other than perhaps making these large caps more volatile during a market readjustment or collapse. I also, am not sure there is a better alternative as you probably wouldn't want equal weighting between #1 and #500 on an S&P index fund.
Not a financial guy so am interested in peoples thoughts on this.
[1] http://archive.fortune.com/magazines/fortune/fortune_archive...