firstly
segwit has not fixed malleability.
it created a new TX format that people can use to (at the time) show they cannot perform malleability.
a. people could continue to use old legacy tx formats and still malleate
b. recently due to new feature needs. core devs introduced a new sighash opcode that actually allows segwit tx's to malleate again..

secondly
the wishy washy code of witness scale factor. does not actually give more transaction capacity per real hard drive storage bytes of full block data.
stripped blocks do not contain signature data to validate a tx is truly authentic. thus having a node storing stripped data is not a guarantee to hold valid data or a ability to relay full data to real full nodes. thus no point being a node messing with stripped data

thirdly
the purpose of segwit is actually to change bitcoin to have a new gateway tx format that would allow features to be done that would suit another network (LN)

fourthly
segwit was conceived to edit bitcoin to give bitcoin a doorway to an alternative network.
the other network was not edited to be purely bitcoin functional
the esssence is to eventually persuade users to de-burden themselves of using the bitcoin network and use another network. thus reduce bitcoin networks utility