Honestly they could use another tier. They're effectively useless after t5. You can spend thousands to get top 10 in a hunt and you get like 12b in banks. Anyone saying they're fine is ignoring the fact that it takes hundreds of trillions to get anywhere in the game and doing it the old fashioned way is impossible by reasonable standards. People could deal with a better version of Banks.
Not that it's impossible, but why would you want to do that? The next upgrade Once you get to t7 either costs 50k or 150k banks roughly depending on which route you want to take.
The other option I can see is a scaling version of the bank that loses it's potency gradually as you increase in stats. I don't think this game should be easy but right now the banks are pretty useless around tier 6 or 7. You can save them all for 3 hunts in a row and still not afford a level 1 crew with them.
It's better that they become useless after t5 bc the higher tiers are supposed to be hard to reach. Can you imagine people reaching t10 at the same time it took them to reach t5 (which would be like a few weeks or a month)? pimd would probably be full of stuck up noobs who think theyre all that bc of stats they got from an upgraded pig. Also, i think ATA would prefer for people to stay and explore the game, I doubt they'll bother doing that if they reached t12 quickly. Anyway, we're not supposed to depend on the banks, they're just there to help.
You can outgrow them in a month. They're useless. Even if they were 100 times their current value you wouldn't be finishing the game off of pimd banks