It's a bit selfish to think that the fist world should continue to get richer while the poor remain poor, which is what protectionism would get, alongside stagnation.
Another sidepoint, when people get wealthier the more they spend and the more they contribute to resource depletion. I'm of course in no position to even guess what the optimal average wealth would be but I'm sure having everyone with too much disposable income leads to wastefulness.
On the other hand, let the people at the bottom catch up and let them breathe. That's what we should be pushing for.