I know this game is not technically the sucessor to Master of Magic, but there is a lot from that game that I believe Elemental could draw on to make it much more lasting and fun, so here is a list of everything from MoM that I still find enchanting to this day.

Races:

I know Elemental's races are all man and separated by kingdoms/empire leadership, but I still feel there is plenty of room for non-human races in this game.  Sure, you can recruit fantastic creatures and summon them as well, but I don't feel it is the same.

Myrrian:

The alternate plane/planet made the game truly what it was, with a distinct set of rules, more powerful enemies, races, and spell effects, and the entire plane tower mechanic was amazing.  Guarding key planar towers allowed you to essentially lock down the gateway between Arcana and Myrrian Races.

Soverign Abilities:
Master of Magic's ability list was long, extensive, and allowed for endless customization when it came to your 'Sovereign'.  I've been a little underwhelmed by the available abilities in Elementals hero creator in both quantity and quality. 

Hero Abilities:

Master of Magic had another very extensive list of possible abilities that could be used by heroes that were not shared by the sovereign.  So far it seems to me that heroes are sharing the same weak ability pool that sovereigns do in this game, plus they are all human so far.  Where's the ogre lord hero that is friendly to humans and will work for a price?

High Risk/Reward for attacking NPCs:

Some locations housed very powerful NPCs (several dragons for instance), but defeating would yield the ultimate prize: a top tier hero, a godly equipment, or even a new spellbook.  All of these made attacking NPC strongholds fun and worth it every time. 

Unity Diversity:
Every faction had basic archers, footmen, and calvary, but beyond that there was much distinction between each of the races racial units.  I am worried so far that with Elemental that every faction will have the same basic units (a la Gal Civs 2 where everyone had nearly the same units, but with different skins).  What made MoM so great was that EVERY faction and EVERY sovereign combination yielded different games, especially when choosing different spellbooks.  I have yet to see that Elemental will offer much in terms of unit diversity.  Sure, we can make our own units, but are we going to be limited to archers, swordsmen, and cavalry? I'd like to see some races get flying gryphons, others get enormous titans, and others get cultists/druids,with very different abilities.

Spells:

I know most of Elementals spells have not gone in yet, but we must see: global spells, disenchant spells, buffing spells, damaging spells, enchant/create item spells,  a VAST amount of summoning spells (since we are forced to use human races) for fantasy creatures.  I'd love to see the most powerful spell books also only available from quests or defeating top tier monster lairs/dungeons.

I know there is still a lot left to do with Elemental, but I hope to see some of these things come together before the release.  As much as I loved Gal Civs, I must admit that the fact units were the same between the factions under different skins (sans a few racial components) put me off a bit, and I fear Elemental is headed down that path.