the original poster is in south wales, uk. the uk in general is colder than you lot in usa. also, uk room temperature is not exactly the same temperature as these insects would have in the wild. while it may be true that alot of species "do fine" at room temperature, what is wrong with wanting to offer something more close to their natural habitat? with some species (granted, not p.paradoxa) room temperature is far from fine. even if you disregard all that, you surely agree that they will grow faster at warmer temperatures. for some people this may be reason enough. also i have had some p.paradoxa that are very fussy and reluctant eaters, some specimens of this species sometimes refuse to eat for no apparent reason. warmer temperatures usually open up a mantids apetite, maybe this will be useful with this species?