They want us to give them feed back and ideas for what WE as the community want to see in the game...
I mean I get that, and I've seen those same snippets from the video for combat so far, but again it's all getting scrapped and as a baseline, it's not bad to look at.
The pre-alpha combat stuff isn't terribly innovative and exciting to see, but like you said, it's already scrapped several times.
What I can say is when it comes to a combat system there needs to several things at play to satisfy:
Momentum & Fluidity - combat needs to be pushing forward, start and stop mechanics kill engagement and immersion. The more seamless the better for combo stuff, obvious exceptions to this exist in the form of big boom specials and such. For all it's flaws warframe does to momentum correctly and also adds to the mix with unique combo stances per weapon, which is something I'd like to see here as well, so that a flail plays differently than a halberd, and a single hatchet is different from a dual hatchet (beyond just limiting casting and more physical damage).
Chewy & Chunky - enemies need to be able to take a hit and give a hit. One of the things that a lot of studios are getting wrong lately. Enemies often get overly spongey, or paper thin as the game goes on. Another issue is the Arkham problem, where it "feels like" there are a bunch of enemies trying to get you, but really, they are just lined up to try to hit you one at a time. This creates the "batman illusion" where you are always winning and always the bad ass, but never in any real danger. The reason this kinda needs to be fixed in this game is because batman is very mortal. When playing the undead we are not mortal but supernatural, and the enemies need to be buffed a little in the smarts division to compensate for that... ie, you may be a vampire, but try not to get surrounded by 4 hunters with silver swords and armor because they won't politely wait their turn to attack you, instead use a movement ability to reposition. The proper balance of chewy and chunky means that I am in a state of constant risk v reward, and that is when combat is most satisfying not only to play, but also to stream.
Progression & Augmentation- Character classes need abilities to select from and associated custom ability trees to create complexity and depth to how one customizes their playstyle. This is also true of a character passive tree (either unique to the class or each class starts in a different area, leaning towards the former for balance reasons). Trees can get out of hand like PoE, which while I really enjoy that game, you kinda need a math degree and make it your life's work to achieve top level success. I believe there is a good middle ground between PoE and Diablo 3's dummy customization. I feel like Last Epoch has a passive tree for characters
and abilities and is probably be nailing it, because you have enough depth between the two sets to create something very unique and complex so that even people that play the same class can vary wildly based on the abilities and passives they augment. The main difference is with Last Epoch they view classes and specializations more like how each class might play in the trinary config, at least that's my impression. Customization of weapon quality is also another thing where micro-optimzations need to be at play, otherwise that quickly scales out of control and balance goes out the window.
Fun & Wow Factor - This is entirely subjective and you can't really give feedback on this till there's a playable demo, and even then, that's to say nothing about the longevity of the system. Really to test this you need to complete a playthrough with the worst gear and passive picks and aternately the best min/max gear and see where to tune it so that it's still possible to be completed by the former, and still not an exercise in brain death due to boredom to do the latter. Generally the best way to do this is to make combat have micro optimizations rather than giant discrepancies that scale out of hand faster, while making progression feel just meaningful enough that it's worth doing. Having a unique and interesting playstyle for each class also falls in here, as well as some nifty animations, and I think with the states thing, if they handle that well, will be enough to give combat a unique identity in this game.
That said I'm not sure that any of that isn't something the team isn't already painfully aware of. I'm not a game developer and all this stuff is readily apparent to me. I'd be very concerned if this stuff wasn't "the basics" from their standpoint.
There are other cool things to possibly discuss like movement and traversal powers and how in depth that can go on our wishlist, but I think generally more options would be better than less (obviously there is a cap on this for choice paralysis). Personally I hate when there are surfaces you can't climb as a supernatural being. Why can't I float up while in a mist form? Stuff like that which is all wishlist sorta things and that really needs more presented from them before I can really speak on any of that because we don't know what's being implemented yet and not. Other stuff like destructible scenery is fun, but how much of that can go into a persistent world is also highly questionable and also bring up things like world states and how people can use that to troll other players (ie, lets say a quest giver has a farm, he gives a quest based on which state the farm is in, destroyed or not, but if it's always destroyed by players then you can't get the other questline, it might make more sense instead that if their farm is destroyed they have less off a reward to offer). This is one of those things where too much player freedom can limit other player's freedom, and that of course, will be abused by players.
There's probably more I'm not thinking of at the moment, but that's all just baseline player expectations I feel, and giving more feedback, i can't really imagine unless I understand more about the systems in place, which we haven't even finished character archetype reveals yet.