The large variety of playable races is kind of an important part of it. The uniqueness and vast strategic and tactical diffferences between the races combined with the huge number of combinations of spell books and wizard retorts cannot be understated. From what I've heard (that spell research/tech trees will be fixed to each faction), EWoM is going in a totally different direction.
There won't be a large variety of playable races, but there will be a large variety of playable factions. The differences between factions of the same race can be as big as the differences between different races. Sure some things might not make sense, like giving one faction the ability to fly or breathe fire, but that's such a small subset of possible differences that you're hardly limiting yourself by using fewer actual races.
Based on what we've been told so far, there will be two core tech trees (one for each race), and each faction will have some techs unique to them and will be barred from researching some others. The mundane tech tree was never intended as a vessel for variety between factions. Your concerns regarding being limited based on faction in magic is definitely valid and I do share that concern. Even if magic is limited based on faction (I hope it isn't), hopefully we'll still be able to retain MoM-like freedom when setting up a custom faction in sandbox mode. Either way we hardly know anything about how magic is intended to work, so it's way too early to make an informed opinion about it. Right now we're making guesses (and not the most informed guesses), and then judging a game we've never seen based on those guesses.
I'm not totally sure what you meant by it, but adding extra layers of micromanagement and then adding automation to solve it seems like a pointless exercise. This was one of the reasons MoO 3 really sucked.
Because it really isn't as simple as that. Yeah if there's something that you can completely automate away so that the player never has to (or would never want to) go in and get their hands dirty - that's a sign that you'd be better off without it. However, there are all sorts of things that would add micromanagement that players won't want to bother with most of the time, but would love to get into some of the time (depending on the person, of course - can't please everyone).
An example of something that I personally would like is a Camp 1 or 3 type economy system. Automation could largely take care of resource transfer, but I'd still want to step in here and there in special circumstances. Personally I think the added benefit of such a system would be great (it could function as the foundation for all sorts of great features including resource raiding, supply lines, etc) - and it's something that can be automated to reduce the time one would have to spend, but still give you the manual control you'd want in order to retain strategic depth. It's clear you don't agree with me on this particular example, but I'm just giving an example where extra micromanagement that is largely, but not completely/always, managed automatically is not a pointless exercise.
If by "heartripping" you mean sneaking past an enemy's frontier and ambushing his fortress, I really don't see a problem with it. Sure, it's a problem in MoM, but I'm expecting the AI in EWoM to be far, far better. Not only should the AI know how to properly defend its fortress, but the AI should attempt "heartripping" against the players. With good AI, I don't think you need a negative reinforcement mechanic like supply lines to artificially make the game harder to win.
It has nothing to do with sneaking past anything. You don't sneak - you barrel through at full speed. It isn't just a problem against AIs, either - it's a very effective tactic against players as well. People are a little better at protecting themselves against this strategy, but that isn't saying much considering AIs have proven completely inept in this department. The only way to effectively cover yourself is to devote so many resources to defenses everywhere, and not just on your border, that you gimp yourself in every other aspect of the game. To defend high-value targets from heart-ripping, you pretty much have to have whole defensive army parked there indefinitely, and that isn't really viable. So really, there is no good defense against heartripping, and that's a sign that something needs to be done to make it more difficult. Not impossible, it should still be a viable strategy if the opportunity presents itself (or if you create the opportunity) - but as it stands heartripping is the most effective way of taking out your enemies in 90% of scenarios.
The reason is that, unless there are only a few small entrances into your kingdom, there is no way to have an effective border defense, because bypassing them is too easy. You need to actually have pretty much full-blown defenses everywhere even well passed your borders. So based on that, the most obvious solution is to do something to enable actual, functional border defenses. This could be done by supply line mechanics (literal or abstract), or something could be done on the defensive side of things, possibly a nice zone of control mechanic.