It is functional in a couple of cases:
* You either aren't planning to move, and want to throw up some cover, or you're planning to move very little, and have MPs left over. IE that 4/6 tank moves 2 hexes to where it wants to be, and burns 2 more MP to get a 1 modifier it otherwise couldn't gain.
* You have MPs to burn on the high end; think Firemoth, Fireball, Celerity. They can get to +4 *while* using Swamp Beast.
Paul