I think it's unfair to judge them on their own. On their own they're pretty uninspired and don't have a lot going for them. I really like them because of the juxtaposition with the full names they are nicknames for. The entire charm of these nicknames comes from the unwieldy names they are nicknames for.
I guess
Ela would be sort of usable as is but it's nowhere near as interesting as when it's a nickname for the glamorously intimidating name that is
Elżbieta.
https://www.behindthename.com/pnl/109883