On the WT forums people are saying that this is what ruined WoT, but we will find out anyway.
The artillery that made WoT so awful has nothing to do with the Calliope or those type of rocket systems. That was actual howitzer artillery that was able to be fired with ridiculous precision. Plus, WoT works off a health-point system, rather than a more fleshed out component / penetration / crew damage system, meaning shells wouldn't just explode, glance off or just damage the suspension, it'd actually damage your entire tank to a point of destruction.
The Calliope also fires M8 rockets, planes carrying this in the game has trouble killing tanks, so you'd need to be hit with a large barrage of these to feel the full effect in the first place. So, given that fact that it's currently premium, has the stealth profile of an elephant, carries fairly weak rockets and will light up on the entire map when it fires, plus you can probably disable that rocket system with a well-placed shot, I honestly see no reason to worry.