I'll preface this with a disclaimer: I have played an obscene amount of Dota. If you already hate me then don't even bother continuing to read because I'm sure you'll hate what I'm about to say as well.
I agree with nearly everything the OP said. Elaboration:
Creeping/Micro: I agree there is no micro with creeps, other than perhaps to aoe them. The main problem in Demigod is that there is very little value in actually KILLING creeps. The gold you get is pathetic proportional to how much gold you get simply by standing there. This was a poor poor design decision in my opinion. When enemy heroes get a gold advantage on your through kills or what have you there is simply NO WAY to make it up save killing enemy Demigods in response. And since they have the gold advantage they have better items, which means you can no longer beat them, barring the miracles of team work. (And that could go either way, assume you still draw if everyone is equally skilled)
As such, you cannot "out farm" the opposition like you can if you go down in Dota. That aspect of the game is completely removed, and Demigod is much shallower as a result. Sure it's "easier" and has less of a "learning curve" but it removes skill and strategy.
Throw in the fact that ganking alert people is simply not possible in Demigod (everything is so wide, there's no hiding places, and you can see nearly the entire map at all times) and it's basically a hero killfest. Still fun, but not as deep as Dota. The heroes themselves are deeper, but more on that in a moment.
Itemization: Completely agree. About half the items in the game are worthless and no one who knows what they're doing buys them.
Helms - Upper left, middle right, lower left are the only ones worth buying. Ever. (Sometimes middle left) Vlemish is such a clear cut obvious choice and outperforms all the other helms in value. That's just the helms. Similar things occur in most other categories. Mostly to blame are the craptacular Minion Boosts that are factored into so many of the item budgets. Half the heroes don't even benefit from this, so you get a poor value for the item bought. And some general builds simply don't care about the stats on your minions. So why do so many items have this crap on them?
Certain accessories are just worthless, and some, like the Heart of Life, are mandatory for every hero and every build. This is clearly unbalanced. There's also far too much reliance on healing potions. I think the cost for them should be increased.
Hero Diversity: Agree that near the end of the game the dps heroes win, with some stuns thrown in here and there. Set damage abilities scale poorly. This isn't as dissimilar as it was in Dota, but in Dota there were abilities CLEARLY meant for creeping. Creeping doesn't exist in DG so those AOE abilities well suited for wiping creep waves aren't so effective later on against 5k+ hp heroes, and you didn't gain a gold advantage along the way like you would have in Dota.
As such there's only really 1 build per hero that works well, with some variation here and there. (There are other builds yes, but they don't work as well) Anyone with a stun must get it.
I have hope here though that they will eventually buff/nerf everything into balance where the crappier abilities are usable. In time I hope they can get it right. It took time in Dota too.
AI/Pathing: Good god they need to fix this. Even more importantly they need to fix the GODDAMN ABILITY TARGETING BUG. Er...sorry. I get really worked up every time the memories of trying to heal myself as Sedna and dying because she just stood there and froze and nothing happened.
A lot of people seem to be against these concepts because they either haven't played Dota, despise anything about Dota, or think it would be "too hard."
If you haven't played Dota, don't get indignant. Dota is still the pinacle of this style of games. I've given up playing it but do not think for a second that Demigod is a better game - it is not......right now. I play Demigod because I see the potential for greatness in it. Each hero being deeper is something that Dota lacks. The flag system is kinda cool (despite every game being just a flag caporama right now).
If you despise anything about Dota - give it a rest. This game is extremely similar. Most Demigod heroes directly steal ability concepts from Dota heroes and sometimes mash a few heroes together. You're playing Dota. Oh wait, no you don't hate Dota, you hate the Dota community. Another misnomer - the same community exists in Demigod already. Leavers, elitists, noobs, the works, they're already here. Sure TDA were a bunch of jackasses but you can hardly call them "the community."
If you think it's "too hard" - so what? Every game does not need to be "easy to learn, difficult to master." The concepts that you find "boring" or "unfun" in Dota gave it extreme amounts of depth, and let people truly get better at the game. You could play without worrying about last hitting or denying, just attack the creeps and if you kill them you kill them and you could play the game fine. You could pick a lane and stay there. You could not try to gank people. But if you put effort into these things you would get tangible advantages over people who did not. It's called skill. That's the point of competing in an online multiplayer game. Don't fear "complicated" game mechanics - master them.
I'd respond to more things but I'm getting tired of writing this long post. Be back later, perhaps.