Eloy: We discussed this at the time as it originally was moved on a move icon rather than the whole block header. We (Ruslan and I) felt at the time that it was easier for users to move the whole header. This also gives a more consistent feel with the movable dialogues (activity chooser, file picker, etc). That said, it wouldn't be difficult at all to change to this behaviour.
It's quite easy to delete blocks or hide them, but at present showing a block presents some challenges with the JS. We did do a proof of concept for this with the intention of working on it for Moodle 2.4 but time hasn't allowed us so far.
In summary, we can easily add Delete, and Hide, but Show is a lot trickier at present.
If someone could make a decision on the Move icon, we can make any changes required there too.