First, obviously, is to support the cable(s) during all anticipated g loading. It probably does not matter if the spacing is 1 inch, or 1.25, or 0.75... There is probably plenty of strength. Exactly 1 inch sounds like a nice round number for the convenience of the assembler and inspector, not an exact engineering requirement.
Second, is so that the cables don't flex, rubbing against other cables/wires in the assembly or any nearby structures and abrade through insulation. This requirement is there for the long haul. A few more hours flight time with marginal ties isn't going to make any difference. If you're looking at thousands of hours over the lifetime of the aircraft, yes, you want to minimize this effect. But a dozen more hops? I doubt it would make any perceptible difference.
I think AA got it in the shorts from the FAA. I'd have flown on any of those aircraft...
But engineering requirements don't matter if you're a power-mad bureaucrat trying to show the productive and profit-earning people, who for some unfathomable reason have to do what you say, who's boss.