We have more and more heroes who’s stats are available for a very limited time. Say Atlantis or Valhalla heroes can be viewed only when portal is opened.
Seasonal heroes and heroes of the month are even worse.
Of course, there is internet and this forum where we can find screenshots, but it is nice to have a glossary of all heroes in the game itself.
Additional useful feature is to see there stats at different levels of ascension. It is very helpful for making a decision whether to ascend a hero or keep them at 2.60 or 3.70 or whatever intermediate level.
Search by name is needed.
Grouping by color, class and family is also nice to have.