Checkpoint blocks are an interesting topic, but there's a mile between checkpoint blocks and "full nodes don't validate transactions so why bother keeping that block data around?".

They're also not about trust, they're about protecting against DoS attacks:

https://en.bitcoin.it/wiki/Bitcoin_Core_0.11_(ch_5):_Initial...

Even with checkpoint blocks, a full node can elect to validate it's entire history if it chooses to, which again is a far cry from "block history data is worthless because full nodes don't validate it", a flagrantly untrue statement.