I might agree with your analogy, voydangel, but the RAW states pretty clearly:
Indirect Combat spells are treated like ranged combat attacks: the caster makes a Spellcasting + Magic Success Test versus the target's Reaction. Indirect Combat spells generate a spell construct at the point of origin (the caster) which travels down the mystic link to the chosen target (see Choose a Target, p. 183), whereupon it discharges and the effect defined in the spell description manifests.
Some spells can only be cast on targets that the caster touches - these targets do not need to be seen, but the caster must succeed in an unarmed attack to touch an unwilling target of such a spell.
So
Step 3 of casting a touch spell requires an unarmed combat vs reaction test, per page 183. Okay, no one disagrees there.
But, nothing in
Step 3 changes the rules on page 204 that state that the Spellcasting test (
step 4) is treated
like ranged combat. Therefore, by the RAW, you get your reaction twice, albiet the second time takes a -1 penalty, since you already defended against the unarmed attack (subject to the additional rules stated on page 204), now you're defending against the spellcasting.
Also note, unless on full defense, the victim doesn't add dodge to his die pool for the spellcasting opposed check, since it is handled
like ranged combat. Nothing in the RAW says "treat an indirect touch combat spell like melee combat".
As to the live wire example, that's a wire, not a spell. You have to
touch the person then
cast the spell. It would be like if you touch a
wire, then, subsequent to that, someone throws a switch and it becomes a
live wire. You have the opportunity to react to the person throwing the switch.
If you don't like the analogy, then house rule it. But, the RAW itself doesn't leave a lot of room for debate. No one can point to a part of the RAW that says "for indirect touch combat spells, since the mage is already touching the target, the target may not defend themselves against the spell".