That's right. But some skills complement each other and others oppose each other. I doubt anyone here has bought more than one melee, one ranged and one shield Expertise. There's no point! You can only use one melee weapon at a time, so why specialise in five different types?
It would be if certain weapons would be highly ineffective against certain monsters.
A blunt weapon should be more effective than an axe, which should be more effective than a sword, which should be more effeective than an arrow when used on a skeleton.
If the effectiveness of wepaons on monsters is played out better then it could be interesting to spend points in more than 1 melee weapon.
