One thing I would like to see is to be able to warp back to ember steps using town portals, cause it warps to Act 1 town, and the map resets (Currently using this to my advantage by going back to the same floor, the glitch one cause its small to level, really dislike the bosses spawning portals though, I can click by mistake / loot can be near it frustrating, I prefer if it was like kill all enemies red portal spawns in a specific place away from mobs and sends you to next level).
Or your idea of having ROD eventually work as a hub, meaning you enter ROD from ember steps and there are many warps to different areas, (the different maps). Then when you completed x number of maps (of your preference, you can pick the map) the boss portal opens (in the main ROD area) that takes you to a random boss for the kill quests. (then repeat)
However don't know how much coding that would take to change it
I very big on using town portals and never using the send pet to town. (I dislike it, it takes way 2 long for the pet (10 seconds minimum is all I could wait for not minutes and had a mod in TL1 to make it such)/also I can't store stuff, I know summon chest is a scrolls but I think that's a bit much/cheating)