Totally agree, and that's something that irks me from time to time... it also applies to the movie version of Themiscyra. There are two issues here.
a) Themiscyra seems to consist mostly of temples, palaces, council halls, and other grand public buildings. It looks similar to the way Hollywood depicts Rome or Athens. In reality, the temples and palaces made up a very small percentage of those cities, and most of the inhabitants were no philosophers, priests, artists, or politicians, but craftsmen, tradesmen, workers (not even talking about slaves). Most of Rome consisted of slums and multi-storey tenement blocks. Why do you think Rome burned for 5 days? Hint: it wasn't the great marble palaces...
Where do the amazons build those flying motorbikes, and who builds them? Where do they do mining, farming, etc., and who does it? Or 'does the Lord provide', i.e. all the things of everyday life are provided by the Gods via magic???
b) I find it impossible to believe that a 'warrior society' can exist for thousands of years, just sparring every day. Either they would go soft over time, or they will go to war from time to time. Anybody who has _been_ in an army knows that peacetime duty is boring and makes people either dull, or aggressive. An army always needs to be occupied in some way. In peacetime, the Roman legions built all those roads (that lead to Rome...), or drained swamps, cleared woodland, and whatnot. Otherwise, they would get up to funny ideas like plundering the civilians they should protect, or stage a coup and make their commander the next emperor.
Even if we assume that the amazons are more noble than the Roman legions, at some point they will get bored of sparring. This may actually explain the frequent civil wars that occur on 'Paradise Island', e.g. 'Paradise lost' by Jiminez, or the Amazon/Manazon war in the Finch run...
which, however, tends to diminish the number of amazons, unless they _do_ procreate (sex pirates...).