That comment is incomplete, the first two Orbiters (Columbia and Challenger) always had a nosewheel steering system (NWS)...but it was only used for the first 4 missions, and got turned off for years due to the problems discussed below.
The original system was inadequate: it was zero-fault tolerant for loss of hydraulic pressure, for one thing. It was redesigned after the Challenger failure (as were many of the Orbiter systems, including the brakes) to remove inadequacies in its design.
A diagram of the original system can be found in the 1982 press manual.
The text-only version of the 1988 update to the press manual has a terse description of the modifications:
The nose wheel steering system was modified on Columbia (OV-102) for
the 61-C mission, and Discovery (OV-103) and Atlantis (OV-104) are
being similarly modified before their return to flight. The
modification allows a safe high-speed engagement of the nose wheel
steering system and provides positive lateral directional control of
the orbiter during rollout in the presence of high crosswinds and
Jenkins, Space Shuttle, 1992 edition, page 243 states
Columbia and Challenger were delivered with a nose wheel steering system that proved to be ineffectual at controlling the Orbiter during rapid transient maneuvers at high speeds. While a solution was investigated, the nose wheel steering system was deactivated on OV-102 and never activated on OV-099. Discovery and Atlantis were delivered with the plumbing, wiring and fittings for a nose wheel steering system, but none was actually installed pending the design of a workable system.
Note OV-102 = Columbia and OV-099 = Challenger
Summarizing the next paragraph from Jenkins:
Columbia - improved system installed for STS-32 and subsequent
Challenger - still had original system when destroyed
Discovery, Atlantis - improved system installed
Endeavour - delivered with improved system
Thanks to David Statezni for pointing out that the original version of this answer was incomplete and prompting me to do this revision, in his answers here and here.
The Shuttle Crew Operations Manual gives a schematic of the upgraded system showing the addition of Hydraulic System 2 for redundancy. You can see from the diagram that this had the added bonus of providing hydraulic redundancy for nose gear deploy. (The main gear was only deployed by hydraulic system 1, and had a pyrotechnic backup release system).
The "Direct" mode of the system - which put the system in a non-fly-by-wire mode and controlled the steering directly from the rudder pedals - was removed and replaced by a redundant avionics system. You can see in the yellow picture above that the original NWS switch gave the commander a choice of GPC/Direct/Off (where GPC is the computer-supported mode). The picture below shows the switch to control the upgraded system, where the choices are System 1/System 2/Off.
The linked manuals have extensive descriptions of the original and upgraded system should you wish further reading.