ranger and colorado) are midsize pickups. The t100 was a midsize that was replaced by the first Tundra. The first gen Tundra was considered full size, but was lighter duty than the competitors F150, silverado, ram. The second gen put it on par with other full size models.

Compact trucks went extinct. The ranger was ended, and the colorado upsized. The ranger was then a midsize when it returned years later.
Likely reason-people want 4door crew cab trucks to take families in. You couldn't fit two 10 year olds in the back seat of the old extended cab compact truck. Ever ride in the back seat of an old s10 extended cab? It might not be roomy, but 4 adults (that aren't excessively obese) can ride just fine in the 4 door tacoma.