I like it. As an employee, it also takes the pressure off for me to be verbose and match the formality of my managers emails. And a simple explanation like "I use short emails because they are quick and easy. Please don't read too much into the tone" the first time around would allay an employees concerns.

It leaves some things unsaid, but better to say them once. Like I sometimes reply "OK" or "got it" to a long request by a manager when I have nothing further to say, but if i DO have questions/concerns, they know I will say more. With that shared understanding, receiving an "ok" saves us both time and energy. Its really great.