Doing so would be going back on their word and original selling point. This would only serve to make them less trustworthy in the future. They actually did try to bring them back at one point, but when Artix was made aware of it, it was stopped the same day.
True but shipping can be very expensive and a lot of Hero-Mart items haven't been restocked in years. Some Hero-Mart items did return in some ways including Flavescent Friday, Sepulchure (changed colour, that's it) and that example you listed.
Hopefully at the very least, discontiued/very old items will return.