Because it's embarrassing to wear a watch with obvious visual flaws.
I don't like wearing a watch knowing that there are flaws that someone like me can spot from an arm's length.
I also never post pictures of my reps online because of these reasons.
Granted, I would never buy a Franken watch when the gen costs 3000 since the cost of building a good Franken is usually above 2000.
But for something like AP ROOs, spending 3000 to build a Franken doesn't seem totally absurd.
I haven't done it yet but I have spent 500+ on some AP reps just modding and stuff so I guess I'm only half way there.