They aren't gonna, because they specifically did say both the tomes and the exchange would be going away at the end of the event. Technically speaking, it's on us for not reading the fine print.

But I do agree in that this was a bad change for them to make anyway, because as most of us know, they had set a precedent with all the previous moogle tome events -- a precedent that led many people into thinking the exchange would still be available simply because that's how it's worked for the previous events.

There really wasn't anything good that was going to come out of SE "altering the deal" like this.