Sota-san (and respective Astar Core Team Members):
Thank you for bringing this issue to the community for an open and honest dialogue. I am nothing but a small investor in the Astar Network, but it is easily one of my favorite projects/protocols in the entire Polkadot ecosystem. Regardless of whatever you, the team, and the entire community decides, I will still continue to support Astar.
Having said that, I completely concur with both @DrCAO and @fouad that comparing the inflation of Astar and its tokenomics to the FED’s benchmark rate is missing the mark; while they both appear to be “high” in a nominal sense, there is no real correlation to these benchmarks. I specifically wanted to hone in on this as part of my commentary because of what you stated toward the end of your initial statement: that we may see Astar’s inflation rate adjusted up or down with some frequency.
While I have no qualms with what the community decides for how to solve this thorny, complex issue over the long-term, I do not think inflation should be a moving target that gets adjusted regularly. This will likely cause confusion and consternation among current (and future potential) investors, which is why I believe this part in particular should not be considered.
Personally, as a Bitcoiner, I like the first model you mentioned where perhaps there are halving cycles during the life of the network that slowly reduce the amount of new tokens being issued into the system. Perhaps that, combined with a similar EIP-1559 burn mechanic, we could reduce the circulating supply over time to the point that Astar becomes even deflationary.
While there is still much to discuss around this topic, I wanted to at least offer my perspective. I also believe that, ultimately, a decision of this magnitude should be voted on-chain so that all token holders can have a say in the governance of the network. I, too, have found it unsatisfying that certain proposals are decided off-chain, and even then by only certain individuals who have the requisite credentials to do so. If we truly believe in decentralization as we espouse we do, then all token holders should have a say in a fair and transparent on-chain vote.
Thank you in advance for your time and consideration of my commentary. I wish you and everyone else working on the Astar team or building in this community the very best 
Gratefully,
Ryan / Phunky