Actually several. The majority of Polk County's rapidly growing population works in either metro Orlando or Tampa and a good portion of Eastern Hillsborough residents work in the Lakeland area. The line would also attract tourist traveling between Orlando and Tampa, as well as offer a viable and affordable alternative method of transportation between the three growing metros, other than I-4 or US 92. As for getting dropped off at a station will no where to go, there would be express bus routes, taxis, other forms of local rail, etc. to get around. In reality, a rail station is no different from an airport. What do commuters do when a plan currently lands in Tampa or Orlando?
The same line Orlando uses, runs through Lakeland/Plant City and terminates in downtown Tampa. There's also a N-S line that runs parallel to I-275 near USF and Busch Gardens, as well as another line that runs near the airport, through Pinellas County, terminating in downtown St. Pete.