Here's my 2p. Firstly, the adaptation of machinery to the rules is nothing new. Look at what happened to mopeds in the seventies under the rule 'must have pedals and be 50cc'; result, the FS1E where the pedals were effectively footrests and a 50cc engine that would drive it to 50mph.
As to safety, what proof do we have that these new microlights are less safe? Or more safe? Have they been flying for long enough to establish any kind of record? Would it not be better to establish that there is a safety case to answer, before answering it? And if they do turn out to be safe, what about relaxing some of the parallel restrictions for their 'bigger' brethren? (Some hope, I know.)