Can't tell you what puts other players off, but I can tell what puts be off this game Well, aside of no Linux support and no Vulkan for my GPU, so even lack of Linux support is irrelevant.
The main issue is, and IMO, it's quite fixable - massive scale RTS games are pretty damn different. And I have no idea what kind of massive-scale RTS game AotS is. Is it like some Total Annihilation mods (like recent Planetary Annihilation is) with dozens of hardly distinguishable units for no apparent reason? Is it frantically fast-paced? Does it have naval warfare? What kind of story is expected? Multiplayer? Etc, etc...
Sure, most of this information is diggable - there is a bunch of PR-buzz on Steam store page promising you glory and enlightenment, but who buys that. There are FAQ's, but who reads them. There are tons of subjective reviews that needs to be read, understood and cross-matched to get pure facts out of them. There are streams and lets' plays that are usually some kind of horrible mess that you must suffer through bad jokes and annoying comments of a player who is dumb and unfocused enough to miss out some obvious things you see on his screen, etc. But - that's require some effort and we all understand that an effort required to understand what such a complex game is isn't small by itself. It doesn't get any smaller by all this issues. So, that's what keeps me off - I know about this game. I kinda want to try it out, but I don't know what it is and I don't have much motivation to get know.
So, what's the solution? Well - give me the facts! In simple and compact form. IMO it would be great to see some kind of "concept tree" of kinds. Like - what's AotS about? What's the highest concepts a player will be dealing with while playing the game? That's probably something along "Building", "Fighting", "Story" and "Multiplayer". These are not strictly separate, but they shoudn't be. It's just a way to classify the information, so I can only jump first at what I care the most - would it be Story or Building or whatever. So what's "Fighting" about - "Control", "Transportation" maybe? "Units", etc. What's about "Control" - well, that's your "Meta-Units" thing for once. "Automation" - that's a big topic you may learn a great deal about from Planetary Annihilation discussions, etc. It should also has something like "Big scale, low-rate, decisive gameplay" - which means that you are operating at high level, makes decisions rather infrequently (in general), but they have drastic effects. Unlike, say, Starcraft where you make lots of decisions like "which skill to use" or "should I move this unit a bit further away", but making a mistake isn't usually that much punishing than a strategic level mistake. Of course, Starcraft has a strategic layer too, as well as AotS has some about of micro, but that's about generic concepts.
So, once you have such tree of reasonably high-level concepts (there is no need to go below "Meta-Units", for instance, so it would hardly be deeper than 4-5 levels) you can present them as a web-page with clickable short labels with somewhat illustrative text. For instance, if you have thing like "Large-scale" there should be an illustration of how much "large" is: "approx. 10000 units per battle at once side mid-game!" for example. And a screenshot with lots off units from the strategic view. So you can get a taste of how exactly "large" it is.
Such web-page will make a LOT in terms of pre-purchase understanding of what it is, while not being particularly hard to make. It will take some time to design an exact tree and choose words carefully, but I suppose you already have some kind of design documents internally which may just already have a similar structure. The emphasis is not on current state of the game, but rather concepts and how you think things should be. So, for instance, if there is no naval fleet, but you intend to add it some time in future and already have an idea of how it will play out in conjuction of other forces - that's a great tool to show it too. And with actual information. So you don't need to check if this review was made a year ago and since then a couple of new races were added already.
For a more specific folks, like SupCom fans it would be nice to see what long-standing issues SupCom had (like air supremacy in conjunction with rather boring hit-or-miss air gameplay) and how these issues are addressed in AotS as a separate "comparison sheet" of kinds. It may not mention SupCom directly as it might be problematic from legal part, but hey - people will understand. At least it would be nice to have kind of high-level comparison between different styles of RTS games - CnC-alike, Starcraft-alike, TA-alike, SupCom-alike (which is, IMO, very different from TA). What is different, what is similar.