Good post. And as you say, it's the accusations (cited in Roger of Howden) of serial abduction and rape of women in Poitou that are far nastier (and are stated openly).

The lack of offspring (one named bastard) seems to be a major factor - but given the claims that Richard then passed the women he'd raped on to the soldiery to 'play with', a lack of paternity claims is hardly surprising. Presumably Philippe's mum, whoever she was, was kept around long enough for it to be clear who the father was. There was also his long history of feverish illnesses (probably recurrent malaria, plus whatever the 'arnaldia' was that floored him at Acre): this could have seriously impaired his fertility.