What are the reasons why we do not have VTOL commercial airliners?
Commercial airliners are significantly larger, and therefore heavier, than aircraft with use V/STOL. Because of that, it would take more fuel and engine power to run that airplane, driving up the cost of running it. There are also many other airframe stress and balance factors that come into play when doing VTOL.
If you are including turbo-prop airliners in your definition of airliners, they could do V/STOL with a configuration like the V-22 Osprey because they are small enough.