I love Selection Mode!
However, I have this issue too, and thinking about it, the fact that the main Selection Mode key - SPACEBAR - allows you to do ALL possible file operations (including renaming, obviously), having Selection Mode trigger for specific operations is actually a massive redundancy UX-wise.
I trigger it accidentally at least once a day, so it is something I’ve learned to live with, but I imagine for non-Dolphin users (or lovers like myself) switching to KDE, this can end up being something that drives them away.
After all, the KDE dev team (for Dolphin specifically) did dumb-down Dolphin for a wider audience, so this is another step in that, but one I don’t think Dolphin users would actually have an issue with.
As a compromise, we could make it so that the Selection Mode key can be either modified to a user’s liking or have additional shortcuts. But there is no need for a “Rename Mode”, “Delete Mode”, and whatever other modes exist that I haven’t found by accident yet, which is how I found the three that I know of. 
Lastly, as I said, the main Selection Mode key allows ALL file operations, and pressing F2 instead just limits the options shown, without actually limiting what can be done.
For instance, if I go into “Rename Mode”, I can still press Delete to remove files. And If I go into “Delete Mode”, I can still press my custom shortcut for a Service Menu script that sends the files to a specific folder. And so on, and so on.
It really is redundant.
PS: I actually just remembered two three other modes:
- “Copy Mode”: press “CTRL+C” while nothing is selected
- “Move Mode”: press “CTRL+X” while nothing is selected
- “Duplicate Mode”: press “CTRL+D” while nothing is selected