What I like about socket type I is that it has both 2 and 3-pin variants, which is a nice feature. And you’re right about how stable it is, given how the pins are angled.
However, from all the images I’ve seen online, it seems to me that those cables aren’t at the bottom or the top, but toward the center. I mean, if you had something like a sofa or a bed pushed towards the plus, that would cause egregious amount of damage to the plug. Now, I could be in the wrong here.
Also, the ground isn’t tall enough, as screen in type G, D or M, which could be a safety hazard. And the point about the accessible fuse, which is a plus in type G, apparently doesn’t seem to be in any other socket.
In support of type F socket, they’re socketed - as in, a significant part of the plug has to go in first. And this interaction enables the plugs to be grounded first, before any of the other pins come into contact. You’re getting both stability and ground connection at the same time.