Learn English – “Hence” and “hence why”

Google Ngram shows the usage more or less steadily falling from 1810, when it was almost 9 times more common than now. From the shape of the graph, one gets the impression that it was more common still earlier to that.

It is a lovely word, easy on the ear.

"Before the cock crow twice, thou shalt deny me thrice," is not only in the King James Version, but in other translations as well.

"Also" when used in the beginning of a phrase is usually used to introduce a new point. (In any case "also" usually refers to the previous clause)

"Also, have you considered using [z]?" - here "also" is just used to introduce a new topic and the meaning is equivalent to "Why do you want to use [x] and not [y]? Have you considered using [z]?" Whether 'z' was meant to be used in addition or as a replacement to 'x', or to 'y', is unspecified.

Alternatives:

"Have you also considered using [z]?" = you should consider using [z] - again, whether [z] is an addition or a replacement and to what, [x] or [y], is not known.

"Have you considered also using [z]?" = you should consider using [z] as well as [y] or [x] - whether [z] is an addition to [x] or [y] is still unknown but in this case it is not a replacement

The question of whether [z] would be in addition/replacement to [x] or [y] might be obvious from context but not from the grammar:

"Why do you want to drink water and not tea? Also, have you considered drinking coffee?" - is coffee in addition or as a replacement? And to what, tea or water?