Actually as much as I like MoM for all the good ideas it had and mechanics it introduced to games in general it did have horrible balance. The "strategies" you seem to be suggesting are more like the title of this thread, that is exploits. Exploits are abuses in the imbalances that exist in a game and aren't intended to be hidden strategies for the players to find.
The strategy of taking all of one book type and summoning a really powerful character was a common strategy in MoM. While most of the people you know may have choosen the Life magic route for Incarnation spell there are lots of general strategies on MoM around the web. And a lot of them involving going heavily in one field of magic and then summoning some uber units.
This is a great rush tactic in MoM because the early game units are no match for the high level summoned units. Also there are lots of pre-existing neutral cities which it's quicker to capture then trying to expanding with your own settlers. In fact that was true so much that choosing a race often became pointless cause you'd soon end up with lots of varying cities since war mongering to capture neutral cities was a much faster way to expand.
As for the artificer/runemage combo I have to say I don't recall how profitable it was but I do recall the higher the mana cost for an item the longer it took to enchant. Thus it could take a long time to see a return on some of those expensive items so I don't really see that as too big of an exploit since your casting is tied up in the enchanting process. Also heroes were great when properly leveled and equipped and that tactic seems more like a late game one to really pay off. So I don't have as much issue with it as I vaguely recall doing it once myself which was fun but very long term. While the other summon rush tactic was sending units that could single handlely wipe out whole armies.
What I do hope that the developers do though is add some more uniqueness to the choices we make under customization like MoM had. Right now most of the options are simple little local bonuses with very little effect on the game in general. It would be nice to see more emphasis on empire reaching effects that change how you play when customizing your sovereign instead of simple local bonuses of a strong unit.
At the same time more unique options among the factions(aka races) like there was in MoM. Each race had buildings it could and could not build, as well as unique units too. This really added more flavor to your starting choices as not only would your leader choice matter in terms of spells and empire wide abilities but the race effected how your cities would be handled and the units they could train there.
For those who haven't played MoM I'll list the traits you could pick and how they effected a players style rather then just copy pasting from a manual which might mean nothing to someone who hasn't played.
- Alchemy: Player could focus on a vast economic empire and use the gold to get magic easily.
- Archmage: The ability to cast in less time and harder for enemies to dispel made it good for enchantment spells.
- Artificer: Starting the game able to creating magic items and at a reduce cost means you focus more on using heroes.
- Channeler: Removes extra mana cost from casting combat spells away from fortress(Capital). Thus they are more likely to use lots of combat spells since it's cheaper.
- Chaos Mastery: Nodes (Kinda like Shards in MoM only not quite) of chaos give you twice the mana, chaos spells research twice as fast, and chaos spells are twice as hard to dispel. So basically a real boost for someone looking to focus on a single line of spells.
- Charismatic: Paying 1/2 cost for recruiting heroes and mercenaries means this player is more likely to raise a large army through wealth rather then building it themselves.
- Conjurer: Summon spells cost less thus the caster is likely to have focus more on magical units then training.
- Divine Power: Mana generating buildings have higher output and unrest is lower. Great for people who focus more on larger cities rather then capturing nodes.
- Famous: Increase how often Heroes and Mercs offer to be hired. Usually comboed with Charismatic for a player who wants to have a large merc fighting force.
- Infernal Power: Same as Divine Power only for Death users instead of Life.
- Mana Focusing: Effectively makes all spell casting cheaper. Thus handy for players seeking to cast a lot of spells.
- Myrran: Player starts on the "dark" plane which often means fewer rival wizards are around. Mostly for players looking for a challenge as the neutral cities and goodie huts often have much more dangerous units in them. But the increase rewards and fewer players to worry about can give the player some breathing room.
- Nature Mastery: Same as Chaos Mastery only for Nature.
- Node Mastery: The increase mana from all nodes means this player will want to heavily focus on capturing as many nodes as they can.
- Runemaster: Arcane spells (MoM's Basic) are harder to dispel and cost less to cast. While there aren't many good arcane spells that I can recall the creation of magic items was an arcane spell which as mentioned above made this a nice trait for those looking to equip their heroes.
- Sage Master: R&D speed was faster making this a good choice for those seeking the path to spell mastery. The closest thing to MoM version of I guess the space race if I were to compare it to Civ.
- Sorcery Mastery: Same as Chaos Mastery only for Sorcery.
- Warlord: Unit automatically gain extra level and have higher level cap. This is important because in MoM summoned units can't gain levels and only normal units can. Thus a warlord benefits more from having an army of trained units rather then a bunch of magic ones.
Much like E:WoM is now the traits cost points which also were shared with the spell books you could get. But unlike E:WoM it wasn't an all or nothing deal. Each book you put into a field gave you access to more of the 40 spells unique to it's line. And because the spells you got were mostly random there was a drive to get a lot of books in one field to ensure you got the spells you wanted. Thus it became more of a balancing act on do you want a lot of traits or a lot of spells. And since some traits tied into some spells books it also is a choice of being better in that line or having more spells in that line.