If all the tires have ths same gap between the tread pattern, then I'm
sure that is part of the design.  If you look at all the tires
available out there, pretty much no two will look the same.  It's all
in what the engineer/designer thought would work best.

It sounds to me like you have a problem with one, or maybe two tires.
It could be a defective tire or poor balance job.  Wherever the tire
was originally placed on the car made the problem very pronounced and
when you rotated them, you put it at a place less noticed.  (Past
experience has shown me that front locations telegraph problems more,
while rear placements mask problems.)

Check your wheels for balance weights.  Do some or all have really big
chunks of weight attached?  If you have three with small to medium
sized weights and one with a really big chunck, the wheel with big
chunck is probably the problem.  If you find a situation like this,
you can ask the tire store to rotate the tire 180 degrees on the wheel
and rebalance it and see if it requires less weight.  That could cure
a problem caused by an technically in-spec, but marginal balance job.

If you actually have a defective tire, I'd suggest rotating the tires
back the way you had them, and then try taking off first one front
wheel and then the next and run your spare in that position.  If you
run the spare on the right front and the issues go away, then there is
your problem tire.  (Obviously check the back wheels in the same
fashion if you didn't find a problem with the fronts.)

As for dealing with NTB, I can't help you.  I will say though that
most chain store businesses won't quickly admit fault/fix problems
unless you can back up your assertions.  I don't know who teaches
these people, but it seems the theme is the same:  the customer is an
idiot and doesn't know what he is talking about.  If you do a good job
of troubleshooting and push as hard as you need to, you will likely be
taken care of.

Matt
Focus owner