It's just not good for a defensive military alliance when two of its newest members decide not to take part in exercises. Especially when they say the reason is not financial. That would have been an easy excuse.
Of course, the exercises are being held in Georgia, at a time when the Russians are really squeezing Saakashvilli. The near abroad is taking Russia's sphere of influence much more seriously these days. I wonder if the strategic mandarins in DC can read the tea leaves as clearly as the Balts?