"From" implies to users that every previous output is owned by a person, is controlled by a person, or is even an address. None of these are always true (though they usually are), which leads to disasters like people sending "refunds" to shared addresses. It's not a concept in the reference client and should be avoided to prevent more confusion than blockchain.info has already caused.
If I spend a script with no hash160/p2sh address, where is it "from"?
Ah, I see your point now. I agree it can be confusing to a non technical audience but presumably, this tool is for people who have prior knowledge on how the block chain works.
It's probably best to avoid using the term anyway. Blockchain.info should really only be a technical tool but non-technical people seem to insist on using it and misunderstanding it.