My question is about Hijab: why do some people say that wearing Hijab is a choice that they made? I thought it was recommended that Muslim women wear Hijab? (I wear Hijab but I was just wondering about this).

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Know, as stated in the Qur'an, Sunnah and consensus of Muslim scholars, that Hijab is an obligation on every pubescent Muslim woman.
So, she has no the choice to put on Hijab or not, since Allah Himself, who ordains prayers, fast and Zakah, orders the Muslim woman to wear the Hijab as well.
In simple words, a Muslim has to say: 'We hear and we obey'. Allah Says (interpretation of meaning): {But no, by your Lord, they can have no Faith, until they make you (O Muhammad SAW) judge in all disputes between them, and find in themselves no resistance against your decisions, and accept (them) with full submission.} [4:65].
For more details concerning Hijab, please read our Fatwa: 82174.
Allah knows best.