- They don't have access to the original books. Either they sold/gave them away and are coming back to the hobby or they want to try the game out for the first time. Retroclones serve this purpose well. They are an easy, cheaper and still largely compatible option to play older style games without actually buying all the old rulebooks. This also works for a DM who has the rules, but whose players do not; as long as they are all willing to switch.
- They like the presentation better in the clone than the original. Many of the retro clones have better presentation and organization than was available in the original works. This is true for clones where the rules closely mirror the originals. It is also true for those who would have preferred slight rule changes, fixes or house-rules that seemed logical, but weren't available in the out of print games. But in this second instance, where the rules are still largely the same as the original.
- They want to create new material for original games. Though it is not necessary to play the games to do this it helps. Because newly printed material must closely abide by copyright laws, it is always wise to at least playtest such games in the retro clone environment to make sure the new material abides by the clone's restrictions.
So in my opinion, and my opinion is of course law (snicker), there are three reasons to play a retro clone and they are listed above. See, when I was playing OSRIC, it was because I was trying to install 1e as our game of choice in the RPG club which I advise. But getting lots of younger gamers to amass the rulesbooks was unfeasable. So we went with OSRIC. I was squarely located in reason number 1. But personally, I firmly believe that only reason number 2 is valid. Which means there is only 1 reason, and 1 reason alone to play a retro-clone. Wonder why I say that? Well, first let me ask you all out there in webland: Why do _you_ play retro clones?