They're all under 10m but yeah a marauder can kite the bubble.
The bubble takes like 5k damage before it's popped, you can build some range and attempt to move away then hit it with a ranged attack like deadly throw that roots and get back on them.
Unless the formula's changed, its more like 4k. At least, that's what my sorc's does and he's got just over 1900 willpower (1396 expertise). It's just barely over 4k.
I've got more will then the vast majority of fellow sorcs I see in WZ's.