I trust your experience, but as you suggested, your explanation is totally wrong. The power supplied to the lights is the battery voltage, which is separately regulated and does not respond in any 'magic' way to the resistance in the bulb circuit. Increasing the circuit resistance reduces the current through the bulb, which is a very effective way to PROLONG its life (at the cost of reducing its light output, of course).
The only way I can imagine by which a bad ground connection can destroy bulbs is by affecting the alternator output. The regulator there senses the voltage between its ground connection (usually to the engine block) and the alternator output. If this ground connection is very poor, the regulator will incorrectly sense a voltage that's lower than actual, and increase the field excitation, resulting in excessive battery voltage. This will not only shorten the life of bulbs, but also damage the battery.
As for the OP's problem, we still don't know what happened there, and if he even meant that his bulbs are burning out too soon. The harness that he purchased is intended to overcome a problem of degraded wiring causing a poor light output by making a short, direct connection to the battery. If, as he mentioned, the OEM wiring had been removed, his lights won't work, because this harness still needs the original wiring to sense when the lights are switched on.
Incidentally, your analogy to ignition does not apply - it's a totally different beast, where the size of a gap in the plug defines the voltage created by a collapsing magnetic field.
You'd get aq better explanation from someone who who knows electrics better.
But basically a bad ground is like a resistor and the voltage increases to overcome the resistance.
A bit like having a gap in your plug wires.
Even if my explanation is wrong, it still happens.
