I don't see the logic in going from 1x the amount of an elected witness to 5x.
I'm baffled as to why it's being increased as opposed to remaining the same.
I would guess it is an attempt to reduce the inadvertent impact of the huge reduction on overall witness rewards (clearly directly primarily at top 19) on miners and runners up (i.e. keep their rewards closer to the same as before). It misses the mark a bit -- the miner and runner up rewards still ends up with a net reduction -- but not nearly as much as without the multiplier.
How else would you propose to reduce only top 19 witness rewards (presuming that is a good idea)?