POINT TO MARK! YAY! Capaldi just has bigger hands. :P
Anyway, There's no particular reason he SHOULD have a new one, is there? t's not like Baker/Davison or Eccelston/Tennant really needed to (and yes, I know in the latter example there IS a difference). It's possible this Doctor just doesn't care, or is waiting for this current version - which may have been in operation for close to a thousand years, for all we know - to expire before building a new one. It may be the longest lived iteration of his screwdriver, so it's definitely a hardy old thing.