Although I think this is very interesting to think about, in practice I think it is a non starter.
Even if we all agree that a coin with non zero inflation is better for everyone, it benefits us as individuals to hold the coin with zero inflation- bitcoin. It would never be in our individual interest to own a coin with inflation, therefore no one will, even if society at large would benefit it we did.
Perhaps, but I think there is a delicate balance to create between the interest of the individual and the interest of society, and I think this balance is ultimately what every economy is seeking. One cannot do this in a system in which the primary means of value transfer is of a static quantity, because there is little to no incentive for hodlers to relinquish themselves of these value transfer units, because if they continue to hodl them, they will go up in value. Sure, this is overly simplistic.
And this type of balance is difficult to achieve in a system where the primary means of value transfer is overdynamic - there is no incentive for an individual to hodl in the first place, hence they don't contribute to this society because the society's value transfer system is flawed and lacks value.
So ultimately the goal is to create a value transfer unit that encourages investing in the society in which the value transfer unit is used.
I think that, ultimately, the inflation rate in a currency should be so subtle and on such massive timescales that changes in the function of the currency as a value transfer unit are imperceptible. And I think another focus of the discussion should be the time window in which the inflation is executed. Probably a 10 year smoothing would be a good start.
And indeed, the internal data that such a system would need to use (money velocity) could be gamed, but if the smoothing window is large enough, the transaction fees to game the system will be exorbitant. And even so, if some Large Actor (such as the state) implemented a plan to game this system, what would be the end game? A redistribution of wealth due to the transaction fees going to the miners (if the system remains decentralized).
And ultimately these types of metrics needed rely on a singular blockchain (so sorry small blockists), unless meta-data is also transferred from sidechains