I think this is another really good argument that Expertise dice should refresh at the END of your turn. It gives the fighter a full Expertise pool to parry and protect with (without trying to do a divination on what happens next in combat) and it prevents the 'well, I missed so I get a zillion defensive actions this turn.' It makes the tradeoff real. There's no tradeoff when you miss with an attack - you default spend zero, tradeoff free.