Assalamalikum,
Since you touched up on the topic of the difference between Fardh and Wajib, it is important to know that Wajib merely does not mean Sunnah. Wajib is more or less like a fardh, and should not be taken lightly as a Sunnah.
To get a glimpse of what Wajib and Fardh indicate in the Hanafi Madhab, refer to this thread in the Sunnipath forums for a better clarification. It outlines the difference beautifully. Difference between Fard and Wajib in Hanafi Fiqh - sunniforum.com
We cannot thus deny the act of Niqaab and its importance in the Islamic tradition (note not cultural). We can only act upon it , or not act upon it. Thats a personal choice. Thats where the difference lies.
However, to blame it on the environment to justify NOT wearing Niqaab would be wrong, or to degrade it to the level of a Sunnah only, would also be wrong. According to the definition of Fardh (or Wajib in the case of Hanafi Ullema).
I hope I got my point across. May Allah help us all in attaining his mercy and pleasure.
P.s. No one is opposing Hijaab, which clearly is a Fardh. I am well aware of that speech by Sh. Hamza Yusuf.