He didn't want the Sith OR the Republic getting their hands on that tech, it was too dangerous. Revans plan was to build an army and a unified galactic empire that he could rule and destroy the True Sith with. When that all went to pot he just left the tech there since he didn't think anyone could get to it.
However, The technology that was there didn't just drain power, it also protected itself. It was impossible - until your character came along - to get through all those traps, droids and pitfalls. The reason for that - as we learned when we first entered the place and found all those corpses - was that everyone kept coming at it with armies. The factory was built to defend against that. But when Revan first found that tech he was by himself and he beat it just like we did. Revan didn't make the factory - he found it, it was there when the Evocii first settled the planet to escape the Hutts. They built the city around it and it just got buried. No one could get into it, and since Nar Shadda is deep in Hutt Space, no one bothered with it until Revan discovered it.
You have to realize that Revan wasn't pro-Jedi, pro-Republic, pro-Sith or pro-anything. He had his own goals and plans to protect the galaxy and each faction was a means to an end. He worked for the Sith Emperor - let him believe that he and Malak had been converted - when all the time he was trying to find a way to defeat the Emperor. He found Nar Shadda BEFORE he lost his memory (Malak's attack) when he was trying to build up the kind of galactic power that could take the Sith Empire on. Moving the factory to Dromund Kass would have just given the Sith Empire more power, something Revan had been trying to defend against
Interesting - so Revan found the factory already in place on Nar Shadaa when he was the Dark Lord - it was part of his original quest to find the Infinite Empire's technology?
He was converted by the Emperor himself? I thought he just turned to the dark side over the course of the long and horrible Mandalorian Wars as a means to an end. If he somehow encountered the Emperor, surely he would've known something about the location of the true Sith, and yet KOTOR 2 suggests he had no idea where the true source of the Sith threat came from? Last we heard he set off into uncharted space to stop them?