I don't agree this should be changed.  The repetition helps improve understanding because not everyone would assume that a METAVAR shown once would automatically also apply to its long form.   

Also, showing the METAVAR more than one is a norm.  For example, see this excerpt from "man grep":

     -B num, --before-context=num
             Print num lines of leading context before each match.  See also the -A and -C options.

     -b, --byte-offset
             The offset in bytes of a matched pattern is displayed in front of the respective matched line.

     -C[num, --context=num]
             Print num lines of leading and trailing context surrounding each match.  The default is 2 and is equivalent to
             -A 2 -B 2.  Note: no whitespace may be given between the option and its argument.

     -c, --count
             Only a count of selected lines is written to standard output.

     --colour=[when, --color=[when]]
             Mark up the matching text with the expression stored in GREP_COLOR environment variable.  The possible values of
             when can be `never', `always' or `auto'.

     -D action, --devices=action
             Specify the demanded action for devices, FIFOs and sockets.  The default action is `read', which means, that
             they are read as if they were normal files.  If the action is set to `skip', devices will be silently skipped.

     -d action, --directories=action
             Specify the demanded action for directories.  It is `read' by default, which means that the directories are read
             in the same manner as normal files.  Other possible values are `skip' to silently ignore the directories, and
             `recurse' to read them recursively, which has the same effect as the -R and -r option.