Several issues here.
Firstly, you must include (past and future) dividends. If you include them, and compare the yields of European stocks to nonexistent interest on European bonds, you will see it generally doesn't make sense to invest in European bonds but makes a lot of sense to invest into European stocks. The index you was looking at probably is a price index without dividends.
It's true that US company valuation has increased but conversely this means European companies are bargains currently with better dividend yield. Past returns are past, future returns are future. To obtain good future returns, it makes sense to have an underweight in the US market, and have an overweight in the European market.
Also, stock prices aren't some random process. They have a reversion to the mean tendency. This means that not only do you get better dividend yield from European stock, the chances of the terribly high overvaluation in the US market diminishing and the terribly high undervaluation in the European market vanishing are good.
Finally, I must state this again: note that European bonds don't even yield so much that they would yield more than inflation!
Disclaimer: I have a heavy overweight in the European stock market and a heavy underweight in the US stock market. Most of my money in in stocks, sans an emergency fund.