@papgeo, I am sorry that you feel that way but That is not something we control , guest checkout involves many variables and based on those algorithms works and show the User experience. If PayPal receive multiple or repeated guest checkout request from same IP then it kind of force them to create an account. So that is not something in control of Plugin in general But PayPal.
But when you said that always ask for creating account, can you provide some more details ? Are you the one seeing that or all of your customers are seeing that?
another thing to look is that if you want users to be able to pay with creditcard, did you tried using other gateways other-than Express Checkout? Like PayFlow, or CreditCard Rest, Braintree?