1) I'm assuming you're including the block reward as part of the transaction "cost". That's not a valid comparison, since that is money injected into the network. Even if it was, upon reduction to negligibility of the block reward, that number will drop dramatically. The free market will eventually settle on what makes a fair transaction cost is in absence of a block reward.
Yes, when block reward is gone, that number may drop dramatically, but what then? what about 51% attack? Right now a PoW 51% attack on Bitcoin would cost hundreds of million dollars too, if the block reward is gone, then transaction fees better make up for it, otherwise a 51% attack would become very cheap.
Now if the transaction fee does make up for the block reward, then we are still back to to the original problem, hundreds of millions of dollars bleeding from the community each year, and paid to hardware vendor/electric company.
This is the paradox of PoW, you can't make it too cheap for 51% attack, but when you make it expensive, you bleed money from the community and eco-system.
So my point is, currently the block reward is what's keeping Bitcoin security safe against a 51% attack, that's why it should be included in the cost of transaction.