I’m not sure if storage cost is the major issue here.
Currently, running a full node requires around 1TB SSD, while even 8TB SSD costs around $500, which I don’t think is too expensive even for solo stakers (given that they’re staking 32 ETH)
(assuming we’re talking about the costs in the consensus layer)
Solo stakers are not the demographic we care about. Users should be able to run an Ethereum node on hardware they already have, and it is rare for a non-gamer to have a multi-TB drive, and even gamers rarely have multiple TBs available.
I think that as soon as we increase the block gas limit and allow more operations within one block, we’ll stumble over new limits. Maybe it’s some opcode that is too cheap, maybe it’s the state or history growth that becomes problematic, or maybe, while most users/validators easily keep up, we lose some who would have to stop their operations.
One cool feature of EIP-7623 is the balancing force between much calldata and EVM operations. A block can still have much calldata but it would cost too much to create a significantly large block. At the same time, if you fill your block with many complex operations, there’s no gas left to make the block “big” at the same time.
Also, I wouldn’t rely much on the current avg. block size as it is only that low on the happy path. Blocks (incl. blobs) can go up to 3.5 MiB right now. This big gap between the avg. and the max. is inefficient (client teams must ensure their software can process such big blocks in reasonable time, knowing such blocks are essentially nothing but an attack and have no other usecase).