Or you can take the PF nerf, which also saves the DM time later in figuring out whether to ban or nerf polymorph and shapechange.
Does your PH2 suggest it? Mine only includes it as an ACF. An optional, different way to play the class.
Regardless of whether Shapeshift is better or worse as a system than WS, it has NOTHING to do with animal companion. No one seriously argues that Shapeshift is so much stronger than WS that it justifies taking your animal companion away.
They could of course, have separated the two. Put in "No Animal companion" as an ACF, where the druid could just choose not to have an animal companion (of course, they can anyway). Or they could have been honest and said that they were intentionally nerfing the druid to bring it more into line with melee or for time saving reasons, so that people who took issue with the class could see what they were getting. If time savings was actually the issue, they could have offered the druid some passive benefit for the loss of the animal companion, like a damage bonus or more AC or Hp or mettle or something, that did not take up a lot of extra time in combat.
But they didn't do any of those things. They included it as an alternate feature, thereby suggesting that it was a roughly equal option, then they intentionally nerfed it further by banning the AC. They made it into a trap for the unwary. People who advocate it without pointing out that it is not remotely an equivalent option from a power perspective are furthering that lie.
Finally, shapeshift does not "balance" the druid as you suggest. It brings it more into line with lower tier melee (which could be called "balancing") while weakening it compared with other full casters (which could just as easily be called "unbalancing").