Pray tell me, if these boundaries are so ridiculous, why after 50 years of independence has nothing been done about it?

Why if the 'coastal forrest states' have enough in common have they not just abandoned the northern 'Islamic states' to their own devices? Methinks that is far to simple an option.
You weren't paying attention to the Nigerian civil war (in which Britain ensured) that the separatists were pummeled - or the various separatist movements in Africa.

Why does France have such a large military presence on the Continent? To preserve its colonial sphere of influence.

There's a vested interest by former colonial powers to keep their spheres of influence in Africa intact, but just like in Iraq/Syria, destabilizing agents like ISIS & Boko Haram will make that task difficult, if not impossible.

So the next great thing in Africa is "redrawing of colonial era boundaries" - it will be bloody, but I don't think you'll understand this.