In what way is "Asian" a less meaningless, potentially insulting "generic clubbing" than Oriental

I would think that might be due to the fact that Asian simply refers to the land mass that a person originated from; whereas Oriental is an expression in one man's language to describe or refer to everything that is/was different from his own Occidental experience. When this same language has now become the communication tool for most people in the twenty first century, the cultures that fall under the umbrella term "Oriental" might feel at variance with all the things that the word was used to imply. Especially when it was not a term designed to refer to a specific race or an ethnic group or a culture. It was and is a descriptive term and not everyone or every culture that it broadly embraces, might agree with the characterisation. To the best of my knowledge, it was used derogatorily, much like 'natives'. I am not certain that, all it meant those days was exotic but I have met people who find the term insulting, and I understand that.

The American HeritageŽ Dictionary of the English Language: Fourth Edition. 2000.
The real problem with Oriental is more likely its connotations stemming from an earlier era when Europeans viewed the regions east of the Mediterranean as exotic lands full of romance and intrigue, the home of despotic empires and inscrutable customs. At the least these associations can give Oriental a dated feel, and as a noun in contemporary contexts (as in the first Oriental to be elected from the district) it is now widely taken to be offensive. However, Oriental should not be thought of as an ethnic slur to be avoided in all situations. As with Asiatic, its use other than as an ethnonym, in phrases such as Oriental cuisine or Oriental medicine, is not usually considered objectionable.