Walaikum salaam sister,
There is nothing wrong with wearing a hijaab to cover your hair. In fact, the crux of the argument in my article is only that the 'Hijaab' has not been religiously prescribed and not that it has been forbidden. However. I maintain that covering of the chest has been religiously prescribed by the Quran.
The Quran is completely silent with regards to 'hair coverage' and it remains an individual choice with no religious prescription or objections.
If you are visiting some cultures where everyone is wearing a 'hijaab' and not wearing one will cause you unnecessary distraction then it is better to cover. If you feel you enhance your modesty with wearing a hijaab and that you feel comfortable in it for whatever reason, then please do continue to wear it. This is your right and nobody should take that away from you.
As long as you are modest and your clothes provide you ample coverage without undue exposure that would conflict with the Quran's directives, that is all that is required. After all, the best 'garment' as God says, is the garment of 'piety' (7:26).
However, full coverage in which a female is unrecognisable can be convincingly argued against in my opinion from verse 33:59. The instruction in this verse seems to strongly indicate that they should remain discernable / recognisable (Yu'rafna').
I hope that helps, God willing.
Joseph.