It would be nice to have a checkbox in the commit view (or a prompt when the commit fails, due to pre-commit hooks) to force the commit (-n flag)

GitX (http://gitx.laullon.com/) has this option.

Example of how this works on the command line:

$ git commit -m "Added Readme file"
Pre-Commit message hook failed!
$ git commit -nm "Added Readme file"
[master 2db5767] Added Readme file
1 files changed, 1 insertions, 0 deletions
create mode 100644 README
$