You keep on hoping and supposing. I hope you're right, I really do.
Also, until we hear from a developer, we don't know that anything is being grandfathered yet.
BtA = more flexibility, more use, more incentive to make more characters.
If I get a super duper BtA item that I want to try, well then I'll make a character. Don't have a slot? No problem. Money well spent. Don't have that race? no problem. Money well spent.
But to have a handful of characters that have loot tied to them and ONLY them?
It discourages all the above for me.
I won't TR a guy just because I found some cool loot and want to try it out.
But I WILL make a first lifer, and vet status them so I can play with my new toy unless I don't have any character slots open.
Here's an example: I have a sorceror that I made into my crafter. Most of his good stuff is BtC. I have an artificer I made some time later. A good portion of her stuff is BtC.
If those items were BtA, Turbine would get from me: a purchase of 2 true hearts so I could TR my crafter into an Arti.
As things stand now, I look at my unfun Artificer and just sigh. No way I'm going to grind Cannith crafting up to 100 on another character. No way I'm going to regrind all that gear I ALREADY HAVE when I could just swap it between characters.
So there is a very specific example of how Turbine is losing money from me by making items BtC.
Instead of sales they could have had, I am going to delete my artificer, and just keep my sorceror as my crafter. Now I have a free character slot. Boom, yeah Turbine just lost more $$ I actually wanted to spend.