I get that (A+B), but the funds-at-risk are the same in both described situations!
To open 2x2m channels you need 4m funds and I pay you 10k sats,
to open 1x4m channel you need 4m funds and I pay you 15k sats.
The on-chain fees are obviously higher on the 2x2m channels option, yet it is cheaper for me to buy them instead of 1x4m.
That's what doesn't make sense to me.