I personally would like it to be in the game and would also like to become good at it,so my vote would be for it to be woven into the "smithing" skill through perks.
I would enjoy collecting different cloths and dyes and be able to make own clothing.Would be cool to make your own cloaks,hoods,etc.....and be able to choose the colours of them through dyes.I would like to be able to choose atleast 2 diffrent colours(dyes) for each article of clothing.Like a black cloak with gold trim.
Also tailoring as an odd job would just be another way of making money,which is always welcomed in my books.
I would accept tailoring even if an NPC handled it,but would atleast still want to be able to tell the NPC what I wanted made for me.(my black cloak with gold trim) For a price ofcourse.
Please let me know you what you think and what other ideas you have.