That is true and I haven’t thought about that. But how will PT export AAFs now that it has this ability? It probably won’t carry over either. Or will they extend the standard? 
For really exchanging projects that are close to being done this is a real bummer. But I often get movies that I should mix so all fades are more an “intent” of the director anyway. I seldomly use the fades as they are and have to re-arrange tracks and clips, transitions and crossfades, and re-do a lot of that fade stuff anyway. So to me, existing fades are just guides. But if I wanted to send the project back to PT after being done, this would surely cause problems.