Add keybinds for button slots in the interface, proper grid keybinding. It is a nightmare to rebind every ability for every unit and building. I use ESDF pan and a split keyboard so the default bindings are unusable.
I tried the game during the free weekend and this is a lost sale for me.
You can kind of play that way via “combined ability/train hotkeys”. You select your military buildings, maybe add to a control group and you can grid away. Same with unit abilities.
This will not work though for building construction and individual building management. Maybe one of the reasons it’s not set up like this is that there’s too much variety between civs? Idk, I’ve never actually played a pure grid set up. I can see the advantage, on the other hand I have changed up the building “grid” to what makes more sense to me for some of them, so I don’t really use it for building construction. But for researching/training managing single buildings it would make a lot of sense.
Variety of abilities, units, or buildings is not a problem for grid keys. Every single unit function is present in the lower left grid. Each grid position is assigned a key. Therefore, every function is assigned a key. All modern RTSs work like this.
I was curious about this and it seems that Starcraft 2, AgeIV and Warcraft 3 Reforged offer both grid and non-grid hotkeys, so AoM could have done the same. I see indeed that if you just want to shift your layout to be centred around ESDF it’s a pain, sorry 
I didn’t mean to say that the variety itself is a problem, but that between different civs there’s many buildings that have no equivalent in others, meaning that the grids would sometimes represent very different things, i.e. you can’t just go ahh row 2 col 1 is the building I get my spearmen/counter-cav from. This ofc doesn’t make the grid impossible, but maybe there’s less transfer between the grids of different civs than in those other games? idk that’s just speculation.
The advantage (possible a small one) of non-grid hotkeys is that you can fully change the keys irrespective of what the UI shows. As I mentioned, I use the default grid for everything but the building pane, which I barely look at, where I have changed some of the keys for civ specific buildings, which I couldn’t do with the grid system. Indeed, I was thinking that it’d be a cool feature that if I change the hotkey, the UI actually places the building icon in the appropriate place in the grid.
But overall, yeah I agree it would be a cool and efficient feature, as now every time we get a new pantheon we have pantheon specific hotkeys, even though it could all be handled with a grid abstraction!
I think the best system would be grid keys, but with the option to rearrange the actual UI panes/grids. But I imagine that might be complex to implement. That way you can customize it, yet it still stays true to the grid.