One; he has acknowledged just about everything in the thread. Yes, perhaps more abrasively then is necessary, but Barrier is inherently an abrasive person.
Two; You are ignoring almost every point and post saying you're wrong, and explaining why you are. So in a sense, you're projecting. Quite a bit actually.
But, let's get to the meat of it, and lay this out in the simplest terms possible.
The "Costs" of this change in PvE:
Knockback IOs is handled in PvE builds in, mainly, three ways;
One Knockback IO in their travel power of choice. This change would allow them to slot a Micro into this travel power instead, increasing the rate that they move (Meaningless in PvE content for the most part), and giving them around .2 end/second in combat, if they choose to run their combat powers in combat. This is the case that applies to around 99.8% of PvE'rs
Acrobatics. Most people running Acrobatics are running it for the Hold Protection. This change has zero impact on these cases.
People running 2 KB IOs to avoid specific knockback powers in specific TFs or on specific farms. In this case it would save one entire slot out of an entire build in the worst case scenario.
So for about 99.8% of players, this would mean a colossal buff of .2 end/sec cheaper for a travel power running in combat. For about 99% of the remaining .2%, it would mean no change. For the rest of the people, likely of which could be counted on two hands, it would mean an entire extra slot.
No one has ever said that there wasn't a cost to these changes in PvE. What has been said is that these costs are minimal, have no large scale effects or costs and that it would improve the game more then it would hurt them. All you have said is referenced, vaguely with no real point, argument or attempt at two way discourse, that everyone is ignoring the "Costs" and projecting your issues onto others.
I won't defend Barrier and say he has made all of these points in a tacit and civilized manner. He hasn't. However, at the same time, he is not wrong. That is important. This is very similar to Stamina being made an inherent. In fact, Stamina becoming inherent was far more impactful thAn this. Yet it happened anyways, because the benefits outweighed the negatives. The same in this case.
Yes. It is power creep. No, power creep is not a blank check buzzword like you use it. It is not inherently bad, nor good. This change does remove cost. However that cost is near-non-existent and negligible in almost every/all cases.