Once upon a time there was a porno game called Fate/stay night. It was very successful, spawning a vast multimedia franchise. Over the ensuing years, its naughty parts were quietly played down. It thus gained a reputation for presenting its plot with dignified, sober gravity, and this story was breathlessly analyzed by its many devotees across an uncountable number of internet posts. Some might label all that as being obnoxiously pretentious but nobody can deny that Fate/stay night is a transcendant title.
That said, no matter how fervent the fanbase, puritanical portrayals don’t move swag. Type-Moon is presumably aware of this, which might explain why the older (in franchise terms) version of Lancer got little love from goods manufacturers while Scathach and a number of new, sexed-up female characters from Fate/Grand Order are all the new hotness. It is perhaps a bit unseemly, but nobody can claim to be surprised, either.