It would be interesting to be able to have heroes available in the store that we haven’t been able to have before like N’zoth, Méca-Jaraxxus, King Rastakhan, Kel’Thuzad, Deathwing, Lunara and even find the book packs of heroes there are also plenty of other potential heroes, no matter how you unlock them (Whether it’s packs or a promotion) it would be cool a much more varied rotation of heroes rather than a promotional hero only both - three weeks…
They are doing this but you have to be around during the specific promotion.
Sylvanas is currently available. Before her, King Rastakhan was.
I think they like to limit the amount of content in the store so it’s not overwhelming for people, so they don’t want to put all the heroes there all the time.
A more realistic take:
By only offering one portrait at a time and only for a limited time, they foster a sense of “Get this now or you’ll never know when you get the chance again” which is more generally known as FOMO: Fear Of Missing Out.
It’s also a factor in pre-order purchases.
Unfortunately it was the Lei Shen that was available before Sylvanas but yes you are right they don’t want to put all the heroes but a rotation of three heroes per week would be cool