Not trying to be condescending here. Without waiting for a professional player to do it for you, can you explain how this game in it's current state potentially offers more complex play than it's predecessors of the same genre?
Lets be clear - the argument here is not one of complexity, the argument here is one of depth. Complexity and Depth are two very, very different things. A game with a vast amount of complexity incorporated into it doesn't necessarily add meaningful gameplay depth. Likewise, a game that seems simple on face value might have an enormous amount of gameplay depth. Look no further than the board game Go if you want an obvious example of this. Blizzard actually already fought the complexity vs depth war ages ago with how they handled SC1. People tend to forget, but RTS games before Starcraft usually had far more units and a sprawling incomprehensible tech tree. Starcraft was Blizzard's take on the genre that distilled it down more into its base parts, but without the hilariously unneeded complexity that marred other RTS games at the time. Needless to say, I think it'd be hard to make an argument that Starcraft was lacking in depth due to its relative lack of complexity.
The design behind Heroes looked at games like DOTA/League and took a swing at what made those games fun, and eliminated what was unnecessary for that fun. Heroes shortens game length, and removes the excessively long laning and farming phases that DOTA/League have. In return for pruning those aspects of the game, you instead get a game that's focused entirely on Hero v Hero combat with stronger map control aspects to support it. Rather than having to beat a team in a full (note: even or close to even) team fight 2 or 3 times over the course of 50 minutes, you instead have to win 6+ of those fights over the course of 20 minutes. The end result is that the depth of skill in how to approach those fights for both positioning, skill selection, and just general team prediction (ie: predicting where the other team is, how they'll approach a fight, etc) tends to get rather deep.
As it is right now, there's a huge difference between how a top level premade approaches team fights and how your lower level premades/players approach team fights. You can clearly see differences in skill at every facet of gameplay. Here's a not so short list of factors that have depth when you start combining them in a team format - landing skillshots on a prersonal level, landing proper combos between teammates, zoning people out, isolating targets, proper heal prioritization, proper utilization of up to 5 cooldowns on top of your qwerd, initiation/counter initation, timing when to go for things based on levels/objectives - I could go on but you should get the idea at this point. There's a huge list of things to consider before every single Heroes engagement, and the fact that you have far more of them in a given game when compared to DOTA/League counterparts means that you generally need to pull out more tricks/plays in order to stay ahead of an equally competent opponent.
The thing about video games in general is that in a lot of cases it's hard to remove things from a game to the point where you actually harm the skill depth to any serious extent. It's just that the depth of skill and what people focus on ends up shifting to other areas. Starcraft 2 technically made things much easier to play when compared to Starcraft 1, but the mechanics that powered the game were more than deep enough to still power an intensely deep skill curve. People to this day in SC2 still don't play the game anywhere close to perfectly despite the laments about the game being simpler. Just like no one today in Heroes (especially on the team level) really comes close to perfectly handling team fights, despite the fact that the game has put a larger focus around them.
If there were to be cliffnotes to this post, it'd simply be that there's enough depth to Hero vs Hero combat in these games that shifting the focus specifically to that and removing some of the other stuff doesn't actually harm the skill curve in any appreciable way. Just like in League/DOTA (or most skill based competitive games), you're never going to be able to look at an individual game and say that a team played anywhere close to perfect. The mechanics are deep enough that even among the best of teams there'll always be wide room for improvement. Posts like yours dismissing the game and attempting to call it simple and easy fail to see what's actually going on and how deep the skill in the game already goes.