Not sure how it could easily be undone now and there is probably a reason the witness data is cheaper, but its a bit of a piss take that these are filling up block space with discounted fees.
Discussion
"post-segwit the witness data doesnt go into the UTXOset and can get pruned. so long-term it’s literally cheaper for node operators. On top of that, we want people to be able to do things like complex scripts for lightning, multisig, other contracting. So if those things are now cheaper for nodes, reflect that in the fees" -someone told me this