That's inadequate. I don't want to drag my luggage around the front of the terminal looking for the shuttle bus to the station, wait for it to arrive, figure out paying for the bus (if it isn't free), then wait for a train.
The railway line should go underneath the airport terminal building. If that's not possible, a covered walkway is OK. Many significant European airports are like this.
If a connection on medium/long distance trains isn't realistic, at least there should be a metro (or whatever the 'best' transport the city has, e.g. light rail).
