Firstly can we get rid of this horrible foreign term "ultralight", it doesn't exist anywhere in UK aviation, and outside the UK it means something different in pretty much every country that you visit.
Secondly, Mike - sorry but I think that you are oversimplifying things enormously. Aviation has huge numbers of distinctions,e.g.
Amateur built PtF
Historic PtF
Type Approved PtF
Private CofA
Public CofA
(and these last two can be divided into normal, utility and often aerobatic)
Then we have more divisions:
Microlight
VLA
Up to 2000lb (PFA)
Up to 5,700 kg (part 23)
Up to 7,000 kg (light)
And that's just single engine.
Then we have licencing:
NPPL (PPC, M, SEP, TMG)
ICAO non-JAR PPL
JAR-PPL
BCPL (any of those left)
CPL
fATPL
ATPL
Then we can rate then: IMC, night, IR, ME, Tailwheel, VP, complex....
All of these assorted categories get treated differently. Whilst one could sensibly argue that the whole thing is far too damned complicated (and I'd almost certainly agree with you), the general approach is that the more potential for public/passenger risk, the greater the regulation.
Microlights at one end then (and I'd agree that they are still just another aeroplane) are at the lowest end of speed/energy/mass/pax/overflight permissions, and so they get the lightest touch treatment. Fair enough, but that's no reason to feel aggrieved at their existence, any more than at Bose-X's enormous number of hours each year - he pays for it in cash, regular tests, and so-on.
Me?, I'm just not flying enough this year and am not a typical anything, but usually manage 70-100 hours each year.
G