Chaosmancer
Legend
Because the gold prices get too high man. I don't want to be tracking hundreds or thousands of gold income from several different buildings when I could just have 1d4 points, total them up to like maybe 20 points total and see what I want to do. And I don't want to crunch math on how to maximize huge amounts of gold when I can just use the metacurrency to do it. Furthermore, I think that since D&D has now moved far away from the old days of relying on a lot of gold, it makes more sense to rely on metacurrencies for things like this.
If it was just spend gold on a big fancy building and that was it, it'd be good. But if I have to keep track of gold going in and gold going out, I'm basically playing landlord + real estate agent and that is NOT what I want to be doing.
On top of all that, given how absolutely stupid most things are in terms of prices (for gold), it just introduces a lot of complicated math when I'm trying to figure out how much to pay the people living in my bastion. Every time my bastion increases I now have to update my huge amount of gold merchant spreadsheets to account for new workers. It sounds like the complete opposite of fun, and it sounds very time consuming. And, since a lot of currency at higher levels is earned through gems and art pieces, I have to then go through selling that, negotiating all of it, totaling up the gold, deciding how much gold goes to my basic living expenses, how much I'm using on equipment, how much I'm using on Bastions, how much I'm paying my employees. Making this system gold just adds SO MUCH.
Bastion points are you roll a die, save or spend the result. Easy. Streamlined. That takes a few seconds to do and lets me then focus my brainspace on the more enjoyable details of the Bastion System.
I just imagine a gold-based Bastion-system requiring a Bastion Turn be an entire session where we're all busting out calculators on our phones and doing longform math. That is, for me, the complete opposite of fun.
Now if I'm being fully honest, I don't think gold OR Bastion Points are necessary. I think there should just be a Bastion Check and different buildings have different modifiers. You choose which checks you want to make, roll them, and reference the individual buildings to see what your check can get you this turn. You could use a CLock system for long projects, like magic items and building defensive walls, and checks can take one or more segments off of the clock. This streamlines the system into an appropriate 5E game IMO, removing any and all bookkeeping.
Why would you have to calculate paying your workers? You don't calculate that now.
I mean, sure, the gold numbers would be higher, but I don't see having five buildings giving you a total of 625 gp to be much different than rolling 2d4, 3d6 and a 1d8 to add together and save the points towards an item.
Personally, my main issue with the Bastion Points is the name is stupid. It should be called Influence, because that's the entirety of what it really is, but if we went gold, I don't see it being any different than it is now. Heck, right now I need to spend 200 gold in the smithy to make a 400 gold suit of armor AND generate 1d4 BP that are added to my pool of BP. You are tracking gold going in and out anyways.