You can take a crowbar and straighten anything, but some things can't stand the strain. You do not screw around with it. Foal hoofcare is essential. Regular maintenance at this most important time is preventative maintenance. The height of the nail has nothing to do with whether the horse is going to be quicked or not.
High nails are generally good nails.
They help because they're not on an acute angle, so if the horse rips a shoe off, he's not as likely to rip hoof wall away with it. And they're usually into more substantive hoof wall. Hotwalkers and longe lines are useful tools, but it concerns me that they're often used to excess. It creates repetitive uneven weight loads on the fetlock, pastern and coffin joints.