As for your new argument, this is something I can partially agree with. If the landscape allows for such immoral behavior and thereby as a consequence requires everyone to adopt the same immoral behavior as a means to survive and stay competitive then I can't fully blame you for your actions.
That does not fully excuse it though. A Man dying of starvation may have no choice but to kill and eat his own child. The situation does not absolve the man of all guilt. Obviously, your situation is not as extreme, but the similarity it shares with you and your circumstances is the fact that you having no choice does not make you completely innocent. Apologies to everyone reading for the extreme example, the extremeness of the example helps fully elucidate the moral ambiguity associated with hard choices.
Also self justification flies far, people will come up with all kinds of excuses to give merit to their own actions. Is exploiting those loopholes truly absolutely necessary for survival? Or is it something you tell yourself without really knowing the full details? I don't know your exact case, but the above is a common trope people use to lie to themselves. People will refuse to look deeper into certain details that make them uncomfortable so they assume a reality that best justifies their actions.
A business that tries to do the "right" thing in a system that allows everyone else to do the "wrong" thing, will not survive.
Is it wrong to not offer a new mother sufficient time to bond with her newborn and breastfeed her newborn for a minimum year per the recommendation of medical research? Yet almost no employers in the US, and especially no employers of lower paid workers can afford to give a mother proper time for maternity leave or to pump breastmilk. The margins are so cutthroat that the business would not exist anymore.
I'm not saying this is comparable to IKEA's tax avoidance, or that IKEA would cease to exist if it didn't do what it was doing. But almost all businesses are doing the "wrong" thing, some more than others, but I won't blame them if they're playing within the rules.
However, if IKEA is then using its proceeds to lobby politicians to continue the existence of a tax code that allows it to steal from society, I do consider that morally repugnant and would judge IKEA negatively for that.
In my new mother not being able to breastfeed scenario, I'm not going to blame the individual business for only giving 15 min of break time. I'm going to blame the government, which only forced employers to give 15 minute breaks for pumping milk, which anyone who has ever pumped milk would tell you is an impossibly short time to travel to the break room, setup supplies, pump milk, store it, and go back to work.
I myself take advantage of various tax loopholes, such as the 1031 tax exchange. However, I use it to keep up with my competition, and further, I contribute and lobby those who I can to remove these tax loopholes.