So why are my 36 slot bags being replaced with 30 slot ones from Remix to Retail?
Who am I hurting by having these? And don’t tell me I’m somehow hurting the tailoring market, seeing as how I have 5 Remix characters and 45 Retails ones, plus not everyone participated in Remix. 
This ain’t player power, Blizz. It’s just bag space.
You answered your own question. Remix was an overpowered fun mess.
Should retail be the same way? That’s up for debate, but currently it isn’t.
Mostly because the only other available 36 slot bags are profession bags or the event bags (Hearthstone and D4 events).
Highest you can go on a normal bag that isn’t an event bag is 34 from crafted currently, I believe.
There are 36 slots ones that can be crafted in War Within. So that just goes back to what I said here:
Giorgio A. Tsoukalos, The host of Ancient Aliens, would like an answer to this question as well. This in fact could be related to the formations of so many Ancient structures throughout the world. 
Ease of access. One player can just have 100 36 slot bags on remix, which means every remix character won’t buy into the bag market because they were made in remix.
Probably because you can buy a bank full of them for 10 bronze a piece and it’d kind of make the prof stuff kind of pointless?
It’s actually the work of small bag’s trying to take some of the power back from big bags. little do they know they haven’t the capacity.
I mean, aside from what I said, dunno. Could be they just went with that as a baseline to avoid some sort of perceived advantage of having played a Remix character.
I’m not going to pretend I actually know why they’re doing it.
And again…
My Answer was completely incorrect, but this is probably the real reason, or at least one of them.
Saying “don’t tell me” doesn’t invalidate the answer youre being given.
If it was player power, I’d understand. I’m not even complaining about the ilevel.
But bag space? That’s just silly to me. Everyone still buys bags even now at the end of an expansion. There’s tons of people who will always buy the incoming 36 slot ones. My 5 lousy characters out of 50 are meaningless for a bag market.
Except it is invalid. Because it’s nonsensical.
I’m feeling like they are a little pointless already, that could finish the job. However, if you’re not taking any contents with you from your bank or bags except gold, what’s the harm in keeping your leveling bags?
Per you.
You could log in and get the best bags in the game for doing a single quest an infinite amount of times on an infinite amount of characters. There is no way you do not understand why they are not letting you keep it.
You can quote that all you want, doesn’t change the fact the bags are cheap as hell.
Per logic. People are still buying bags even now. I just had a friend sell 75 of the current ones, while people know there are 36 ones incoming.
Blizz has given no explanation for this and it’s nonsensical to claim “muh bag market” when we know it isn’t.
Not sure what bag prices have to do with me losing my 36 slot bags.
I don’t care that they took them. I care they waited until the last possible minute to tell us they were.
Not everyone did but everyone could have. Some players could have deleted all their characters to make remix characters into their future mains. Most people went in to remix knowing that not a single thing would carry over 1 to 1, which included the bigger bags. Since retail characters could only have two 36 slot bags before TWW, if people assumed that they kept the bags, they could have started “stocking up” for the convenience bigger bags provide, regardless of how insignificant it may seem to others.
One person in this thread surmised that as a potential reason. I dont even think they need one besides they were too easy to acquire and nothing in that mode was ever intended nor stated to be coming over to live when it ended.
You are being put on an equal field as anyone who boosts a character. You didn’t do anything special to earn it, you wont be special when you’re out.