Originally Posted by
Inevitability
The asterisk is not necessarily 'this will be tricky to normally use'. It denotes 'this has an ability that would be completely broken if allowed, and the rating assumes you remove it'.
The problem with 'low movement speed' and 'has to find a host' is that there's no real trait to remove. Take away 1 ft. movement and... replace it with a basic human walking pace? Remove the symbiont's power restrictions when unattached? There's no obvious way to remove
Furthermore: we've rated monsters that wouldn't fit in most dungeons, monsters that need water to breathe, monsters that die from water, monsters that would get run out of any civilized place, and monsters that explode if you leave them out in the sun. None of those traits got them asterisk-ed, because the underlying assumption that they'd only be played in the campaigns that could accommodate them.
What monsters did get an asterisk? Those whose abilities would innately and effortlessly disrupt any campaign. A dryad can't be used in any campaign that involves 'going places'. A shadow can't be used in any campaign that involves interaction with humanoids. An efreet can't be used in any campaign that involves, well, the PCs having goals.