All movies are fan service of one type or another. People only seem to ridicule it when they aren’t a fan of some aspect.
This isn’t the case. The King’s Speech isn’t fan service. The fan service most people talk about is the inclusion of certain things for no reason other than because fans will recognize it, usually to the detriment of the overall film. The “You’ll be dead” guys and R2 and 3PO in RO were perfect examples of that. There’s a danger that they will do similar stunts like that in Han Solo’s movie, such as having Greedo show up and tell a joke about how he likes to shoot first or something. If Greedo has a purpose for being in the film other than to cameo for fans, then it wouldn’t be fan service in the detrimental sense.