sweet jesus, this is the 2nd time now i read up on an thread i haven't read in a while, and people are discussin' the Morality of Monster Girls.
also i Agree, death by sex is one of the better ways to go, at least you got to go out with a bang, bit less in my eyes if the girl screwing you is dismissive of you. i'd rather have Lust-crazed beats sex me to death than a arrogant subbucus.
besides, i wouldn't call the girls in MGE neither evil or good. as TVtropes would call it, they got a case of "blue and orange" morality. they'd straddle you and fuck you into the ground if you strike their fancy in order to make you their own, but by god will they adore and love you and treat you like a treasure, hell even the biggest tomboys of them will learn cooking to make sure you are as happy as they are. tho i agree some of them even make me feel a shiver run down my spine.
at the end of the day, this setting is the highest order of sexual escapist fantasy. when it comes to having fun in the sheets in this world, there are no boundaries. life a loving life with a loving wife, build a Monster girl harem. Let out your inner Alabama and start having fun with your offspring, or just join the sabbath and admit you're a lolicon. the monstergirls don't mind it at all and in fact encourage it. hell, the only reason they even wear stuff like maid outfits or gym-wear is that they KNOW people got a fetish for it, and gladly wear it if it makes ya horny.
yeah yeah. fucking somebody till they love you and all that is looked down upon in our modern era. but thats the point, ain't it? this ain't our world, they got different rules going on. and trying to impose our standards on it is like trying to make America accept the Metric system and abandon their tipping based service industry.
on top of that, the goal of the demon lord in this setting is, to put it blunty, happiness for all. if the order were to win, lots of people would lose their loving, ecstasy filled lives, because someone decided that your way of living is wrong and had to be stopped and accept their way of living, that is deemed the right way to live, even if you yourself will be tons more unhappy about it.
in other words, stop trying to find a moral high-ground and start fucking already, that's what we are here for after all.