It is subjective, yes... but what becomes a game rule is not.
I didn't like X3; I thought it made the game far too much about economic tinkering and not nearly enough about flying around in spacecraft blowing stuff up.
There is plenty of wiggle-room between those two likes. I'm not saying that I don't want any economy at all, I just don't want one where that is the real game- I want blowing stuff up in my fleet to be the real game. Again, look at Mount and Blade- they got it right, despite having an economy that was if anything more complicated than X3's under the hood. Mount and Blade mainly comes down to player skill in real-time, not number-crunching.
The economy should be there to provide a framework for building my fleet, buffing my fleet and building NPC fleets that help me... but if I can't really expect to play beyond the basics without getting deep into economic-sim stuff, that would be very disappointing.
The game's core Fun is what's happening in battles; anything that drags the focus too far away from that is to the game's detriment, imo. I'd much rather see more focus put onto Story- big bad Bosses to kill, gadgets to acquire, stuff to do, than into economic stuff.
Part of it's because I'm a min-max player; if there's an economy and I'm not utterly bored by the whole thing, I'm going to figure out how to abuse it. But I really hate having to play that way to have fun. I'd rather that that part was simpler and my K/D ratio mattered a lot more than ROI calcs and figuring out how to corner the markets to screw up the AI.
The AI is the main problem here; AIs that can actually do much with a really complex economy are very non-trivial undertakings. It's no big deal to make a resource-free AI that can provide a reasonable challenge, but one that cannot be economically defeated and plays without cheating is a whole 'nother story.
Since making the AI actually able to play things well is such a major problem and it's so incidental to whether the core's fun, I'm saying that I don't think it should be emphasized much if at all.
It's one thing, if the AI cheats up new resources when it needs them but can be defeated by manipulating economic rules designed for the players... but if the AI has to follow all the same rules, it's very unlikely to provide a sufficient challenge and defeating it will be mainly about manipulating numbers, not about skill. There just isn't any satisfaction in defeating an AI that way, by starving it of stuff until it can't even fight back, so tbh I'd rather it wasn't even a serious option.
But if it's going to cheat, which it almost certainly is, then there's no point in pretending it's a real economy, is there?
So just build a player-side system that provides a challenge to players, but let the AI do things that provide a challenge. To the player, the economy will be "real"- it will have real rules that provide a decent challenge to get enough resources to defeat the AIs. But don't bother dragging the AIs into that mess- it's not necessary, they're just there to give the player a challenging experience, after all.
This isn't a simulation, it's a video game. It needs to stay focused on that.
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Since all this stuff may be a bit abstract for a lot of you theory-crafters, let's make it simple and concrete.
Let's say that, at optimal production times, it takes five Systems of average resources and fully-upgraded AutoFacs about 3 months to assemble all of the ships needed for one Hegemony SDF.
So, I as the player can kill one of those a week, easily. With just one fleet under my direct control.
How, exactly, is a non-cheating AI going to even come close to dealing with that reality? Answer is... it can't. Period. So it's going to have to cheat. And we're right back to square one, where the AI's reality is different than the player's reality.
Since the above situation, with players kicking the AI's butt in actual combat if they're skilled and buffed correctly is likely to remain the norm, because it's already been battle-tested quite a bit and we know it's fun... I really can't reconcile that with the "real economy" stuff at all.
It just can't be made to work that way- even if the Hegemony has 100 Systems, one player fleet is basically going to wreck it (60 Systems will be doing nothing but building replacement SDFs to replace what I've killed off, which in a "real" economy would totally derange everything), and if I can destroy the means of production and all that implies... there is just no way any AI will be able to deal with it.