It is worth noting that Wedge also increases the damage taken, so it's usually used on cavalry that can charge and skip through a line of damage. Infantry move slower, so they'd theoretically get picked apart as they march in a wedge.
It's also useless defensively (cavalry are pretty much never used defensively) due to that reduced defense and the likelihood that you'll be fortified. BM also doesn't seem to really allow for counterattacks in a single battle (at least tactics-wise), so using a bunch of offensive settings for a surprise turnaround doesn't really work.
