Well the problem with having just sales taxes is that the larger your income the lower the percentage of your income you generally spend on consumption. And for those in low income groups almost all of your consumption is non-discretionary.
On the other hand there are some studies that show a consumption tax does favor investment over consumption - something that is a positive.
As far as stock goes, it really doesn't matter. When you get a stock option it's still taxable income.
The nice thing about owning stock is that the long term appreciation and dividends that you may garner is taxed at preferential rates - again to encourage investment, and in recognition that dividends are taxed twice, once as corporate earnings and again as income.
Hope that people who own a lot of Apple stock have been cashing in on it. I've read too many stories about people concentrating their investments in Apple. Diversification is very important.