During the Amiga and Atari age, graphical games were possible, but expensive (in time, talent, determination) to create. Text adventures were not. Even though platforms at the time could execute graphical games, the developer overhead in creating them wasn't even close to equivalent.
As graphical games got easier to produce, that gap shrank, and text adventures did get less and less vital.
As graphical games got easier to produce, that gap shrank, and text adventures did get less and less vital.