I like a good technical discussion
It's not just about dollars, though obviously they come into the equation. I weighed up the pros and cons, and for me new coils with new casings win over worn out old coils with sticky tape every time. The only way I could have been comfortable leaving the stock coils in there would be if I'd sent them off to be rewound and had the casings fixed/replaced properly. That'd probably cost a fair whack I imagine and would be a bit of extra time off the road, when you can just bung in a set of brand newies and be confident that it'll be all good. To me, trying to fix the stock coils was a waste of the ingenuity and ability you mention when there is an easier and arguably superior method that doesn't really cost that much. It's not almost free, but when people are spending $10k on a car at the very least, often much more just in mods, $500 is cheap.
As you mention, things will fail over time, and there will occasionally be faulty parts out of the box, but I'd hazard a guess at the odds being heavily in favour of new parts. It's also not just about failure, the old coils will probably have a weaker spark than when they were new. Choosing the easy, well-tested and almost guaranteed method isn't a cop-out IMHO, why make it harder than it needs to be? I'm all for DIY but in some cases it's wasted effort, particularly when we're not talking about an enormous outlay to do it "properly".