I think the roller actually helps make it look a BIT more realistic - it seems to help the fade seem more realistic. But, having said that - the more successful fauxtina jobs I've seen seem to do two things:
1) not go overboard (my 2 cents is that the Trucks! job went a little overboard)
2) not go "under"board - i.e. taking a "nice" paint job and squirting a few primer spots and then some topcoat and sanding through it looks very tacky in my personal opinion.
So, what 's the solution? TO do it JUST right! Sorry, I realize that helps you absolutely zero...
But back to your question, I would venture a guess that MOST fauxtina jobs are not done with a roller, and, I think the roller job's texture tends to help the believability.
I agree, many faux jobs look horrible. But, REAL patina is something not everyone isn't blessed with - and faux tina is an option that CAN look good, but it's not quite as easy to successfully pull it off as it may look. And also keep in mind that a good faux tina job isn't necessarily a less expensive approach than an average-cheap real paint job.
I look forward to some pics - by and large I love patina and I CAN like fauxtina. But I do tend to see more jacked up faux jobs than successful ones. So, it's a tough, but very personal, decision for an owner.