Drive encryption is only really securing your data at rest, not while the system is running. Ideally image based systems also use the kernels runtime integrity checking (e.g. dm-verity) to ensure that things are as they are expected to be.
In my case I am talking about myself. I prefer to actually know what is running on my systems and ensure that they are as I expect them to be and not that they may have been modified unbeknownst to me.