Why do some games get modded and others don't Thread

So here's a question I've always been curious about. Why are there some games out there that get modded and others don't? I understand that of course people need to be interested in a game to want to mod it, and that it's easier if the developers themselves have provided tools, but I've seen many games out there which i imagine should have a large modding community but don't appear to have one at all, regardless of whether or not the developers have provided tools. Two examples that come to mind are the Hitman series and Batman: Arkham City. Both Games seem ripe for new levels to be created or characters to be added but both have barely anything beyond a trainer and new skins.

So whats happening in these situations? Are the games simply too complex to reverse engineer for a modding community and there's not enough interest/time to do so, or are there games in which it is impossible to mod them from the game data alone?

A lot of modding community's seem to rely on a few heavy weight coders to develop the tools to mod, when games share parts/engines it may make it much more easy the tools to mod can most likely be shared between them as well; example; the development of mods for GTA V leans heavily on the scene and tools from GTA IV, the first GTA game to use the RAGE engine ( their table tennis game was first tho )

I have no played the hitman or batman games so i cannot comment on that, i would guess no heavyweight tool devs?

One huge factor is the simplicity of the official modding tools. I remember trying to create some levels in the Tomb Raider IV and Max Payne's editors and I gave up after a few tries. The same period, I discovered Half-Life's editor (WorldCraft) and by the end of the day I had made my very first basic map. Simple tools create a basic modding community which may or may not grow, but will provide the basic tools (like tutorials) needed for a newcomer.

Of course, there are other, more obvious factors like the popularity of a title or, as Zomorfius said, if there'll be people who will 'ignite' a game's modding community with their skills, but, I believe, some games are more modded than others because they have user-friendly tools to begin with.