Just tried Eureka for first time...

[Iscah]

...but you can see how people with limited time to play convinced SE to have no respawn time for Skirmishes like NMs have in Eureka.

Those aren't equivalent. Bozja's skirmishes are equivalent to fighting random monsters for EXP; CEs are the NM-equivalent.

That said, I think Bozja suffers from giving no EXP for fighting the individual monsters that trigger CEs, meaning they don't spawn if people are focused on levelling up through skirmishes.