Don't get me wrong, I get the reasons of your worries, I just don't understand why that after looking at the numbers, people are still that scared. I can understand to stay level headed to avoid over confidence, but it's feel like the current fear is irrational imo. The numbers make it impossible for Le Pen.
And when I say taboo, I'm not saying people vote for them scared of repercussions. I'm saying that the taboo comes from the realization of what it could be if they had free reigns. There's a reason why every political leaders call to vote against them. Even Dupont-Aignan still haven't say anything because polls say his voters will vote (at a thin majority) for Macron. I've known a couple of people that have already voted for Le Pen in past elections so I definitely feel what you mean when you say that people consider it more "normal" than what it was. But those individuals are not the majority which still think it's bad to do so. I mean on every polls since the start of this election Le Pen was getting smashed in the second round by Hamon, Meluche, Fillon et Macron. That has to mean something.
Finally, should we trust the polls ? They haven't failed us thus far :
Liste de sondages sur l'élection présidentielle française de 2017 — Wikipédia.
Le Pen is between 30 and 34 currently. 34 is around 12.5M. And the polls thus far give more second hand votes for Macron from every candidates Fillon included. The closest she ever was to win (she was still losing) was some polls against... Fillon ! Interestingly enough, only candidate that was winning every configurations was Macron. So you have in the second round, the candidate who was winning against everybody against the candidate who was losing against everybody.
I don't know breh. Trust us Frenchies a bit