I personally loved it the last (and only) time they had a roster slot sale. I thought it was probably the coolest sale they’ve ever done- mainly because I didn’t know it was possible as they don’t have a flat cost. I spent my entire hoard of HP on slots I didn’t need. I had a bunch of extra unused slots just sitting there after that sale.
Now that newer players/transitioners will be drawing from a much larger pool of characters, the need for roster slots is higher than ever. How about throwing us players a bone and doing another slot sale!? Seems like a win-win for the developers and us as players who are in more need than ever. I guess maybe that’s a reason NOT to do a sale (as you stand to make more money). But I think it could be a pretty cool goodwill gesture!