A lot of this “problem” is playstyle-related. I do agree that there are some things that could be done to encourage a little more active style, but there’s nothing forcing the IB to play defensively or passively.
While I originally (when I opened up the Career, and a while after that) did consider IB nice to play and liked his forgiveness, the novelty wore off after a while as I learned to play better, and as the playstyle was mostly the same all the time. So I got bored of him. Then later, after a few more-or-less random chats with one of my teammates, I picked him up again - with a different, way more active playstyle, and that way found him quite fun to play again.
As mentioned, his Career Skill gives, in addition to 100% BCR, a huge Damage Resistance. That can be used very well, and enables a lot more tricks than the BCR part. I find that actually a far more useful and important aspect of it, as standing around blocking and pushing is rarely that useful, and usually boring (although even it has its places). Far more fun (to me, at least) is to pop the skill and then swing away like a madman, not caring about damage. And frankly, berserker IB feels kinda insane at times.
And that takes me to a particular thing that I’d like to see. IB (as most other Careers) has very rarely-chosen Talents at level 25. In this case, I’d say it’s the extended area (although I don’t think Boss taunt is that often picked either). On the other hand, the huge DR during Impenetrable means that IB is the only Career where I’d consider uninterruptible attacks a useful option. So replace the increased Taunt area with uninterruptible attacks; if felt necessary, balance it by removing the infinite block or maybe even reducing the DR a bit; and thus give us a more aggressive style option for IB, give him some real choice in Talents, and get an actually good “uninterruptible attacks” -Talent.