1) If they were too big, they'd escape the gravitational pull of their planet and either float away or create their own orbit and become planets.
2) The only moons of which I have heard that may be habitable (ie, have some sort of atmosphere) were around huge gas giants (Jupiter).
2) The gravitational pull of small & tiny moons would be prohibitive to maintaining an atmosphere. There does seem to be a descrepancy here as the moons are the same size as the small & tiny planets, however, I imagine that this was done in the interests of expediency.
My two cents worth
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Spyder, Chairman of the Arachnid Consortium
Re: Moons
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