The mempool is a working memory of transactions that could end up in a block soon. The biggest argument used against filters was CBR and nodes not having potential TXs in their memory syncing slower. This doesn't even have that problem since the TX can't show up in a TX in the near future.
Why are nodes providing long term storage to users? They can't even estimate fees in the future so it's a high likelyhood that the TX will be underfunded when the time comes anyways, or the user will drastically overpay for it. You shouldn't be signing TXs ahead of time like that.
And for what benefit?
