Correct me if I'm wrong but the Imperium
does still make Land Raiders. This is an accurate lore excerpt that proves they are still in creation.
The Land Raider has its origins in the Dark Age of Technology, when humankind expanded out of its home system. Its construction method was incorporated into the great STC system, allowing it to be built locally by colonists even if they lacked any great technical knowledge. With the widespread breakdown of human civilization during the Age of Strife, production of the vehicle ceased.
During the Great Crusade the Land Raider STC design was rediscovered, allowing their manufacture. These vehicles were incorporated into the arsenals of the Imperium's forces and used as heavy transports and line breakers as well as mobile command centres. When necessary they could be used as Titan-hunters.
The discoverer is commonly believed to be the Technomagos Arkhan Land who, at the very birth of the Imperium is said to have rediscovered the STC designs hidden beneath the surface of Mars.
When the Land Raider was first deployed by the Imperium is disputed. Some believe it to be as early as the start of the Great Crusade, during a great conflict that raged across the world of Calysto Platinum.
Initially the Land Raider was in wide use through the Imperium. The Anvilus 9 forge world became devoted entirely to the production of Land Raiders.
The Land Raider as well was used by both the Space Marine Legions and the Imperial Army. Throughout the Great Crusade, few worlds were not won without the support of the Land Raider.
At the outset of the Horus Heresy, Anvilus 9 was overrun by renegade tech-priests, halting the production of the Land Raider. Many other forge worlds chose to stay neutral and seceded from the Imperium during the Heresy. The few Land Raiders still being manufactured for the Imperium came from the forge worlds still loyal to the Emperor.
With the dark clouds of the rebellion drawing closer to Terra, the Emperor ordered that all Land Raiders still in loyalist service were to be transferred and used exclusively by the Legionnes Astartes, who were at the forefront of the fighting. The Emperor was never able to annul the order, consequently, even after the Heresy, the use of the Land Raider remained exclusive to the Space Marines.3
Chapters, especially ones like the Black Templars, often use Blitzkrieg-esque assault tactics, which involves tank charges comprising often of multiple Land Raiders.
Strict Codex Astartes Chapters field 10 Land Raiders, as they are only for use by the 1st Company (Which comprises of 10 Squads). And they carry 12 Space Marines, or 6 in Terminator Armour.