This may well be true; but I've found that in actual, real-world interactions, the fact that I'm speaking a non-native language is mostly a disadvantage in decision-making.
I'm normally relatively non-confrontational even when speaking English. But in French, I've found that this is hugely magnified, and I suffer for it. Even when people are being unacceptably rude to me or people around me, I'm stuck being polite and agreeable.
In French, when someone calls me on the phone, trying to sell me something, I'm only now (after 6 years here) getting comfortable interrupting them.
Not long after moving here, I had a clearly intoxicated man invite himself into my house (even though my wife & I had two visitors staying with us), and he eventually even asked to borrow one of my women (because apparently my wife plus the two women visiting were "mine"?!), and I eventually got rid of him, but I never said anything remotely impolite.
I hired a local workman just starting his own construction business to replace the fence around our garden, and he persuaded me to pay in advance even though his incompetence was already becoming clear (and the end result was already falling apart by the time he "finished"). I never said anything confrontational.
These are embarrassing stories to tell; I'd never let things like this happen if I were on my own turf, linguistically. In English I can be subtly cutting, or curt, or strongly rude, or whatever I want with no further thought, when the situation calls for it.
In French, when someone insults me I'm still wondering if I may have misunderstood, or am missing social cues, or if I've accidentally offended them and their behavior is justified. In a confrontation, I immediately feel like I'm in over my head, and taking control of the situation is almost impossible.
It's slowly improving -- my French is already quite good, and I'm relearning how to manage in difficult situations.
But it's been a serious downside I hadn't expected before moving here, and if this is a general effect I imagine it would offset the advantages studied here pretty significantly.