I agree with most of what you've stated here, and how you've stated, except for Dipping. I'd stick Dipping into the problematic category, because of the impact it has on damage at early levels, and the fact that it can be done, with a candle. If it were a scenario, where you had alchemists fire, and "dipped" a blade in it to cause it to light, using up the alchemist's fire and an action to dip, then it would add a cost that would balance out the benefit.
As it is now, if you are within range of anything alight, it's a no brainer to dip.
True, but you can just not dip, which is why I consider it a non-core mechanic. All you gain are some damage points. That said, it's a lot of extra damage points at low level, but it doesn't force you to formulate your tactics around its existence like everything in the bottom category does.
Defenders of the current system like to argue that you can just simply ignore the cheese. That argument immediately falls apart when you simply rub two brain cells together and realize there is no way to play where you can ignore using height advantage and disadvantage, because you'll be affected by one or the other in most given situations no matter what. There's a huge difference between ignoring an option, and having to go out of your way to avoid a mechanic entirely.
Right, the enemy AI seems to have it cooked in that they at minimum will seek the high ground. To at least remain on even footing, figuratively and literally, you therefore have to try to do it too not be disadvantaged at worst.