By the way, I actually didn't understand your idea. Maybe you should elaborate more on this subject.
when OP talks about pre-computed data mining.. and then "storage mining" and "storage costs are low"
he is talking about an altcoin that doesnt hash a block in simple sha256. but some other algo of going back to cpu computing that plays with hard drive stored data (like solving big-data patterns)
where the computers stay cheap to continue to find patterns of pre computed data.. im guessing
thus wanting bitcoin to completely change its ethos, methodology and algo to go back to come cheap CPU scheme of cheap device
..
and now answering that guess to the OP
the only issue with wanting "cheap, low storage cost" mining is... those who want to make profit will just house multiple PC's, so it wont be like the CPU solo mining days of 2009-2010 it would jump straight to 'rig/pool' mining and then farm mining. where by individuals with 1 PC wont get majority of reward but only small shares of a reward.
I'm not the biggest expert in this field, but I don't think that the quantity of miners has anything to do with the security of the network.
actually at a network hashrate of 500exa, with an asic of 200thash.. means there are 2.5m asics(emphasis specialist devices not in everyones home, not easily hacked)
breaking down the cost (each asic being ~$4k)
is a hardware cost of $10billion combined just to achieve 500exa
meaning an malicious pool wanting to 51%
would need to buy $10,500,000,000 of hardware to counter the 500exa clean cooperative network rate of 2.5m asics
if hardware was(op's idea low cost hardware) a $400 PC
to attain the same security cost of clean network (would need 25million PC's) to be a $10b network security cost
but.. then we come into the issue of a hacker using trojan botnets to take over other peoples common PC's, at no cost to hacker
.. so more clean PC's would be needed to counter it
with everyone having a computer EG lets say 2billion PC's online right now in peoples homes around the world, hackers could easily take over 25m PC's without any hardware cost for the hacker. thus a security risk for the OP's new style idea.. so the clean network would need ALOT more then any possible trojan botnet can take over of random users.
in short the clean network would need to have billions of clean PC's, virus free to counter any hacker 51% attack
thus security cost would be more then a $trillion of hardware costs for security..
meaning each individual miner wont get many shares of a reward in OP's guessed scenario
having specialist devices(asics) for mining, means hackers cant just take over common devices in everyones homes to mine, because not everyone has specialist devices.