A suffix is anything appended to the end of a name which provides additional information about the person. It has been a standard part of naming conventions for well over a 1000 years. It includes generational designations (Jr, Sr, III, IV, etc), titles (king of England), honors of nobility (KG, KB, Bt., Esq., Gent.), academic titles (MD, PhD, etc.), military service (USMC, USM, USAF, etc.), religious orders (CSC, OFM, etc.) and a fair number of miscellaneous designations which are completely standard usage.
A title of nobility is almost the definition of a suffix and it belongs no where else. It is the correct and proper usage of a suffix both in and out of genealogy everywhere in the world except on wikitree. A title is absolutely part of a name and the entire point of a suffix field is to have a place to put it. The current system is a joke and I have absolutely no understanding of why you think having a properly structured name, both in form and appearance, could be worse than the mess we currently have. It is wikitree's idiosyncrasies such as this which hurt wikitree's reputation and why it will not be taken seriously in the wider field of medieval genealogy. It is something which just fails the test of common sense.
Style and Standards improvements: The Suffix Field