I think it's great you have a separate window in the vendor menu that points you to a form of item progression.
However, most players have their own list, that can even change during the game. Soon, this default panel becomes obsolete.
It would be great to add the possibility for each player to customize this, so instead of a default "suggestion" list it can become "a list for Hero X". This would prove most helpful during gameplay, removing a large number of clicks through the vendor menus.

My suggestion for this process would be:
1. Make the vendor items list accessible from the Menus, outside the game (like in the "Learn" sub-menu). Here any player can explore the various combinations and think about his/her own builds. (this would be very useful regardless of the following ideas).
2. Create and link a grid-like inventory to each hero. Players could click a Hero, and then click the vendor items list (see pt. 1 above) and select the items they think would work best with that particular hero. You can limit the size and form of this grid to fit the current item "suggestion" list in the game.
3. Add an option to "Save" this customized item list for that specific Hero, once every player has established his/her own item list.
4. The Saved list would be automatically loaded in the place of the current in-game "suggestion" panel for each Hero.