First and foremost. There is a bug.
Ahh, the classic excuse, :-) It's always a bug!
Let's see if we can get to the REAL problem...
RD Minons actually reflect 2 attacks back instead of 1.
My regular gear is enough to handle all other types of Reflect Damage Monsters including the Uber Version of The Siegebreaker.
Okay, let's review...your regular gear can take on Uber Siegebreaker, which, if I've read every possible letter of the strategy guide is, in fact...ONE monster, right? Siegebreaker isn't an army of monsters, right? I mean, I've killed regular Siegebreaker at least seven or eight times myself, so if I remember correctly, Siegebreaker is ONE monster.
Minions, on the other hand, are...MANY monsters? Like upwards of nine or ten sometimes that surround a yellow/rare monster? Siegebreaker, by the way, not a minion. Not protecting anything, he's a boss all on his own.
I notice in your mathematical rant (because, ya know, math proves all) that you call out specifically MINIONS. You didn't mention blue/champion monsters, as those mobs only come in packs of three or four, and unless your AOE is high enough, another tactic is to take out one at a time. No, you specifically mentioned MINIONS, which come in large groups and have a leader, and the fact that those minions appear to reflect back double the damage that leaders do.
Real issue: even if minions reflected back only one attack...it should still hurt badly.
So, instead of being a child about this...why not just divide and conquer? As a side note, I do agree, a gear-switch button would be pretty cool. However, you're right, you shouldn't have to switch gear. Just use a different tactic. The devs put out a video pre-launch where they offered tips on how to handle the infamous Inferno difficulty, and one thing they mentioned was that it's best to have at least one strong, focused, single-monster attack, and at least one wide attack for AOE. If a player JUST does focused attacks, they'll constantly get overrun and can't hold back packs. If they stick to AOE (and stack DPS, like eeeeeeeeeeeeeeeeeeveryone does), you'll run into RD packs which SHOULD rip you to shreds because, mathematically and logically, if a single powerful AOE attack hits a TON of RD bad guys, you SHOULD feel that sting multiplied.
Oh, and before you look over my profile, by the way, and say I don't know how RD feels, trust me, I know how it feels. My top three characters have felt it pretty hard, and at least once, it's caused my Witch Doctor to die. Even with DPS far below 50k and on LOW MP levels, like 0 and 1, it still gets felt.
However, if an RD pack of minions is causing me trouble, I back off the AOE and attack one or two minions at a time. I mean, Diablo 1 was NOTORIOUSLY stupid for allowing you to stand in a bloody doorway and attack one bad guy at a time as they walked through, really cheapened the danger factor. Obviously, in D3, you can't do that as perfectly as in D1, but you can at least utilize some strategy, break up the pack, and pick them off one at a time.
I don't mind people calling out things they think are bugs, and I've really stayed pretty clear of getting on the "Really Blizz? WTF?" train, complaining about class nerfs and making the game easy...but this Reflect Damage nonsense WILL end up getting nerfed in a subsequent patch to the point where it's TOO easy to deal with. Check it...RD packs are MEANT to hurt. They're MEANT to be handled differently than other packs, that's what creates diversity in enemies, and as a result, forces you to use strategy and not just stack DPS, spam AOE and lay waste to everything without blinking. TLDR: Call this a mathematical bug all you like, but as it stands, when I see Reflect Damage packs, I fear it, I keep frosty and sharp, I press on and I win the battle however I can by fighting smart. When they nerf this, or "fix the bug" as you call it, it'll be like RD never even existed. Pray that DOESN'T happen.