make display of letters on index page optional

Would it be possible to make the display of the letters optional on a vocabulary term page? So the list of terms is just presented as a list?

And along the same lines: maybe make it also optional in preferences to display a page with vocabularies?
(so a prefence" "do not show vocabularies index")

I am working on a project where I need the term pages. Taxonomy VTN's ability to display a list of nodes when clicking on a term is unique (it means not having to customise templates).

Gerben