My bet is they're intending that you leave Shoulder Tackle for movement and GL stacks rather than rely on it as an OGCD DPS increase. They could push that point home by reworking the skill itself so that it doesn't deal damage with the tradeoff of increasing potencies elsewhere and then just have Shoulder Tackle traited based off your current fist stance.

I will say that in most fights when I play monk, I don't use Shoulder Tackle on cool down specifically so I can be more mobile and have it help me more easily maintain greased lightning, realizing that this might be a DPS loss overall.