There are a couple of things. One, there is increasing criticism of the stock option deduction from business as well. We find, for example, the former head of the U of T business school saying that this encouraged poor behaviour by corporations. It encourages a short-term type of thinking, and runs counter to the interests of the companies themselves. So there is an increasing critique on the stock options deduction even in business terms. It doesn't really provide any social or economic benefit; in fact it's counterproductive in both cases.
In terms of the differential treatment of income from investments, what we need to realize is that some investments do create jobs and should be encouraged, but more and more investments are actually speculative investments and do little or nothing. In fact they are counterproductive in terms of economic growth and economic development or job creation. Government needs to distinguish between these.
There may have been a point to the special treatment of investment income back in the day when the stock markets were actually a source of capital investment. They no longer are a significant source of capital investment or job creation, so there really is no economic reason to give preferential treatment, especially when you consider that the benefits of this, which cost a huge amount in terms of government expenditure, are going to the wealthiest citizens.
Even Ms. Yellen from the United States is saying growing income inequality is bad for the economy, so we need to do something about closing the income gap. These tax policies go in exactly the opposite direction.