Sure, cash flows are better than dividends, but that's largely due to leverage, which again increases risks; secondly, housing does NOT appreciate much like stocks. Long-term housing appreciation as roughly at, or slightly above, inflation (1% real, if that). Long-term real return of global stocks is 6-7%. Further, built into equity funds are companies focused on real estate development. By owning index funds, you get better real estate diversification.
Not trying to suggest you alter your thinking necessarily, but only become a landlord if it's what you desire to do and you understand all the risks involved.
For many, like myself, investing passively doesn't involve any additional hassles or headaches and allows me to enjoy my free time away from work.