Boy I hate wiring...but you make it sound easy
Tony, wiring can suck; usually because there's just so much of it the spaghetti overwhelms you if you open a harness. Can be even more daunting if you have to mess with electronics or, God forfend, actually screw with a board. This little circuit, however, is an easy one. If you decide to make the change it's not tough at all.
If you do change it there is one thing to keep in mind, however, about whether or not you decide to keep switching the spotlights with the headlights or use an accessory switch to turn them on and off independent of high or low beam. Some states mandate that auxiliary lighting must turn out when the high beam comes on as part of their safety inspection. So if your state checks for that facet of light operation you need to keep it triggered off the headlight.
To do that and still have the spot lights come on if you blow a headlight fuse would still be simple. You'd still use a relay that is closed (on) when it's trigger is dead. You'd still take power from a switched accy point in to the relay and you'd still go out of the relay to the spotlights.
The trigger point on the relay in this case though you'd bring from the HIGH beam headlight wire (instead of the low beam wire it currently comes from). You'd use the high beam feed because it's the one that is dead when the low beam lights are on. That way if the low beam headlight is on (i.e., high beam wire = dead) the relay is triggered and the spotlights shine. If the high beam headlight is on the spotlights are off and your state inspection is happy. But if you blow a fuse and have no headlights then both headlight leads are dead so the spotlights come on automatically without you doing anything. It wouldn't matter whether the headlight switch on the handlebar is in the high or low position because if you've blown the headlight fuse the high and low legs are both dead. Spotlights come on automatically and no sudden unexpected total darkness.
You no longer have the theat of darkness if you blow a fuse because the other benefit to doing it this way is that if someting happens in either the headlights or the spotlights to cause a fuse to blow the spotlight and headlight are now on separate circuits. In the stock configuration they're on the same circuit. So if you lose one you lose them both (which is actually kind of dumb).