Both normal and HC are already extremely easy, even if you've never done them before you can put a group in LFG, set insane requirements and get carried. If the group wipes it's okay, you can always keep inviting more zerglings until they kill the bosses for you.
"But omg they're gonna wipe and it will be a horrible experience!"
No they are not, set ilevel requirements to 880, 890, whatever and they will do just fine. You can easily outgear both those modes just by running WQs and LFR and getting sick titanforged upgrades.
"But omg skill > gear!"
If you are not a mythic raider, this statement hasn't been true for many years now. What's the point of keeping overgeared casuals fermenting in LFR when they could be trying harder bosses and maybe even improving their skills?
"but this will destroy casual guilds!"
It already has, check any realm and you'll be hard-pressed to find a non-mythic raiding guild. Actually if anything, this will help mythic guilds as they'll have more relatively well-geared people to recruit.
Hell you could even enable LFR for mythic and people would still kill bosses. Sure, mythic Skorpyron would destroy them at first, but in a few weeks only the most dedicated would still be attempting him and they might even improve to the point they're able to get a kill.
"But omg no communication!"
Simple, Blizzard uses their funds to create an in-house voicecom and integrate it into the game.
This is coming from a mythic raider who wants to hit queue button and faceroll normal and heroic instead of applying to dozens of groups in LFG.