This is easily the most requested feature for the Hall; your feedback is heard loud and clear. However, behind-the-scenes things have prevented us from adding something like this to the Hall of Heroes, as much as we'd like to. It's not something we can add for U24, but we'll be looking into it for the future, as it's something we know players want.
Stuff in bold has been added in U24 (or, if it was already in the Hall, moved closer to the other things).

We may be able to add more Trainers and types of Vendors in the future, several of you mentioned Spell Components, Potions, and Scrolls.
The purpose was to be sort of a 'hub' space, making getting around easier. In its current incarnation, it has the opposite effect; that's part of why we've moved things around and added a lot more accessibility to things (Airship/Stormreach Teleporter options in Eberron, teleport destinations in the Forgotten Realms) for U24.
This is a good example of a non-constructive post. If you don't like a feature, or even feel like you won't use it after the changes, feel free to say it; telling the devs their time is wasted for making improvements to the game helps no one. At worst, it's incendiary antagonism, which is counterproductive to getting what you want here.
Thanks for the feedback so far, folks! Lots of good ideas here, definitely keep 'em coming. If you haven't checked out the U24 changes on Lamannia yet, I'd encourage you to do so and to let us know what you think of the changes there.
Thanks!