There is quite
an enormous difference between those who are still alive and wishing to stay that way, and giving up everything for those who are already gone. You talk about "will to live", but Shinji says on-screen, in no uncertain terms, that he doesn't care about himself or the world
, so long as... er... he can rescue a dead girl?*
Well, I'm not sure how mutual self-sacrificing rescue relates to old "don't become too close" idea, but "don't give up everything" looks more believable as a message. Except it already was in NGE and what, Q becomes "Let's see how you don't care about world now"? That way at least it would be about Shinji's mistake about what he values, and not about proper control of all-powerful beings. I guess saying "will to live is will to do something" would be stretching it^^. But it still fits in broader pro-egoistic theme, that Misato supports with her encouragement of Shinji to do something not for someone else (yes, she doesn't like consequences, but still supports the idea). And Rei is not dead.
Perhaps you can also explain why, If Anno actually wanted to say, "Shinji is totally doing the right thing", Shinji's efforts result in: the imminent end of the world, his own consciousness going total hikikkomori in Eva-01 (for the next 15 years, at that), and Rei's soul just trading one tomb for another.
I think "because the world is not fair and, like Fuyutsuki said, it is easier to break" is not worse than "because it would hurt more that way" as explanation for why bringing Rei back worked at all.
If you're actually interested in Anno's message, it might be better to pay attention to everything in the films themselves, rather than clutching at straws (a single phrase in the preview and the previous anime series). What Kaji talks to Shinji about earlier in 2.0 is especially worth another look.
I assume it is not about that part, where Kaji tells to protect the girl, so "bad things make kind people", "proof of living" and "not only you, but also my girl"? Shinji helped to create a lot of kindness then. Seriously, "proof of living" sounds exactly like old ideas of will to live as apposed to nothingness. And yes, previous series is different work, but it doesn't mean that Anno now thinks that everything he said in NGE is wrong.
* If the parallels to Gendo weren't obvious enough then, 3.0 has Fuyutsuki spell it out even more.
Shinji saves Rei after that train-sequence, there he told to try to understand his father. So assuming train-dwellers are on the good side, I would say it more a plus for Gendo.