If you're getting stripped that often it's very likely that you don't manage your LP appropriately, you could be letting it pile up. The chance of being grabbed depends on the amount of LP held and the length of a battle (there's also a 2 turn cooldown before a grab can happen again so that the player can recover). Later in the game this becomes important due to the amount of LP enemies give you, raising your lewdness stat will make you resilient against the LP given by those attacks. However, it could also be a case of unlucky RNG.
As for being naked having fewer lewd attacks from enemies, this is intentional since those attacks are LP based and being naked basically generates it constantly. In that state the enemies just want to finish you off. It may be kind of immersion breaking, but it would have made playing naked be overpowered.
Thanks for playing!