Let me put it the way that Frank vdP explained it to me. If you are served off a trolley you have two members of staff multi-tasking several activities in front of you for several passengers. Often mixing parts of service across multiple passengers (e.g. the bread basket pass). If it's all plated - or rather trayed - in the galley the process is that one crew member makes an individual approach to you, asks you want you want and then brings it to you, you have their complete attention for a minute or two. Frank would emphasise the "you" word in that line. And you don't get to see the meal being tipped into the plate, not that you would in the case of JER anyway. I wouldn't say it's a big deal but I can see it is a more personal approach, not least because this way they can check the iPad or manifest for your name in between trays. But yes, on JER it's not worth it.

[Digression, there is one CSM who memorises up to 48 names before every Club Europe flights. I've seen him do it, though he does get somewhat thrown if there is a late seat change at the gate!]