The workaround against both options is to simply split the stake to different accounts.
No, it's not. See A splitting stake to A1 and A2 in my article. He can maximize usage of his stake, but still unable to take all the seats.
Limiting the number of blockproducers that a stakeholder can determine has other tradeoffs so it's a complex problem.
If you can point out these tradeoffs. I can't see any. 1 SP = 1 vote simply allows for better decentralisation. JS made an educated decision about 20 candidates, but the average person would not :)
I can imagine a situation where 2 or 3 different versions of the code are running side by side that create different forks that do not agree on the last irreversible block. Each version being supported by different cartels with no clear way of breaking the tie.