Some Thoughts on Metaplot

Well, as I mentioned before, I am currently working on a larger rpg project, the design of a world setting.
In the course of this endeavour, I am running into many problems, and some of them will hopefully spawn ramblings to be posted on this blog. Here's the next of these ramblings:

In the course of designing the culture for one of the races in my setting, I started to think about metaplot in this setting in particular and gamedesign at large.
First, let me define metaplot for the rest of this post: Metaplot is an ongoing narative for a game's setting as a whole. It can be completely open for everyone to read and take part in, or it can be for the GM only, full of hidden things happening to baffle the players with.
Games with strong metaplot have been White Wolf's World of Darkness games and Deadlands, some other games like Fading Suns do have a metaplot of sorts, but it is very weak and can be ignored quite easily.
Advantages and disadvantages of metaplot are quite obvious, or at least I think so. A strong metaplot keeps things interesting for the gm as well as the players, it offers lots of hooks to hang cool adventures on, giving everyone the feeling of actually taking part in the world's history. The disadvantages of a strong metaplot are very much about freedom.
A strong metaplot can force GMs and players alike in a certain direction, cutting off interesting avenues of adventuring. It also can be very cruel to the GM to be the only one to know all this stuff and never getting the chance to reveal it to te players.
So is a strong metaplot a good or a bad thing?
Frankly I don't know. Of course, a good gaming group can always make up their own world-shaking plot-lines, but this takes some experience.
It's not that this is very hard, but it often takes a lot of self-assurance on the GM's part to tinker with an official setting in that way.
So, returning to my original point: Should I include a metaplot of sorts in the setting or not? At the moment, I'm thinking yes, for a few reasons that I will try to outline below:

First of all, I like metaplot, I like reading about it and discussing it with others.
Secondly, the setting is very well suited for metaplot. It is a very young setting with a short history. So quite a lot of things are happening at the starting point of the setting. Many changes are yet coming to the new world and I think that some of them are ideally dealt with in the form of metaplot.
Thirdly, I'm trying to make te metaplot as optional as possible, so that those who don't want it can ignore it without much hassle.

How will I achieve this? I'm not yet completely sure, but I always liked the idea of optional campaign supplements that can be used to play out one particular strand of metaplot. If the group doesn't want to play the campaign, the part of the metaplot simply doesn't happen.

This may lead to some problems in a future second edition of the setting, but at the moment I'm simply too far away from even a first edition, to bother about this.

The point of these ramblings?
Metaplot yes, but in moderations, I guess.