One house rule I've been mulling over for a while now.
Control ratings from Focus Items and Specializations don't assist the Magic user with hitting an opponent, only to actually control the spell itself. Basically, someone would only use their Discipline on the aiming portion of the roll, thus eliminating the whole 6+ athletics issue. One of the side effects of this is it would make Control more in line with the usefulness of Power. Both have always been fairly useful, but seriously, Control has always been, by far, the most powerful of the available options.
One of the arguments some people I've spoken with in my group voice against this, is how expensive and limited spellcasting already is. It would be a bad to make it more difficult to hit an opponent with a spell, thus easier to waste the limited resource. I've always understood on that, but I've still thought it over trivialized, when you are practically guaranteed to hit every time, unless the GM has some crazy NPC, or the player completely and utterly botch their roll.
The biggest reason I thought this one up, is I never understood why spellcasters should be able to get a constant roll of 8+ easy, without spending a single fate point. They are the only people in the entire system that have access to a bonus like that, and I've never really understood why that was. With how the system was built, it felt like it broke it to me, and I just thought of a way I thought would be easy to try and fix it.