I can understand the desire for Heavy Armor and Sneak. I've tried it.
In Oblivion, it could work. I used Conjuration, so I did the Summon Boots, which were Heavy Armor, but weightless so that you could sneak in them as well.
I don't know if Skyrim will work the same way.
As for why I'd combine Sneak and Heavy Armor - it's simply because I don't want to run around throwing fireballs and arrows everywhere. I like to use Sneak to get myself in to a good "get the drop" position, take the guy out with an arrow, then pop out my heavy claymore and take on the rest of his buddies face to face. Well - face to face with some conjured spirits by my side too
Back on the Oblivion forums, someone made a reference to me of pretending he was a "special forces" type of guy, who'd get the drop on someone with Sneak, then use my Heavy Armor'd tank combat skills to face his buddies straight up.