Arguably one of the main reason we're not able to change (or at least, enforce) the rules easily is because of regulatory capture of tax agencies around the world, and multinationals are (directly or indirectly) funding this regulatory capture via their investment in complex tax avoidance schemes and the whole industry around them which is in constantly in and out of the "revolving door" between regulators and accountancy firms.

So, likely there's always going to be opportunities out there for aggressive tax avoidance, because of exactly these kind of agency problems. And so a multinational is always going to have a decision to make about exactly how aggressive they choose to be. And they are going to be judged morally by the taxpayer for the decisions they make, whether they like it or not.

If they are judged badly as a result of their choices, they should have the good grace to just admit that they're being selfish because they can get away with it and that's the way things are, and not come up with disingenuous self-serving rationalisations.