This was done purposefully I'm assuming. In the comics there is a discrepancy about Ras. In one origin story he was part of an Arab tribe that migrated to China and he used both ancient cultures to come to his Lazarus Pit, etc, in this origin he is slated to be about 600 years old. In other origin story he is of British decent who goes through an affinity for ancient cultures and studies all of the ancients including ancient Persia, ancient China, ancient Japan to find the keys to various aspects of his power including a combination of various ideas and theories to create the Lazarus Pit in that origin he is just under 500 years old.
Both Wannabe and Neeson played both aspects of the origin perfectly IMHO but it should be noted that the British decent (Neeson's take) is what is still considered canon for most writers in that universe. Ras does wear a suit most of the time, only followed by his emerald cape which if you added to Neeson's suit from the end would have fit perfectly.