I don't see how this would make the glyph any less mandatory in order to be competitive in PVP as MM.
Without glyph:
- Aimed Shot can be used while moving
- Aimed Shot has no CD
- Aimed Shot has 3 second cast time
- Steady Shot can trigger Master Marksman
With glyph:
- Aimed Shot can be used while moving
- Aimed Shot has 6 second CD
- Aimed Shot has no cast time
- Steady Shot can not trigger Master Marksman (Pointless since the 6 second CD prevents you from getting more than one off every 6 seconds anyways)
In other words, without the glyph, you MIGHT get an instant cast Aimed Shot every 6 seconds but only if every single Steady Shot gives you a stack of Master Marksman and you do nothing but cast Steady Shot in between Aimed Shots
or with the glyph, you are GUARANTEED to get an instant cast Aimed Shot every 6 seconds, without having to use Steady Shot or relying on procs. Yea...that doesn't sound like it's mandatory for PVP at all...