WOW. Lots of deep thoughts here. Hmmm! My opinion(S) are It depends. It depends on the purpose of the Map/ artwork . A map by some definition is a optical representation of an area/object with the purpose of helping on navigate through/to that area to achieve a purpose . Certain additional information is usually necessary to obtain the goal efficiently. A schematic of a circuit board is a map of sorts. It works much better if it denotes in some way which parts are which and where. A layout of your kitchen cupboard is much more efficient if all the pertinent items are labeled so you can find the peanut butter behind the sugar bag.
In real world maps it is more important to follow stricter rules to be universally effective. Still the Navigation system in the auto though hardly handcrafted is still a digital map as it gets you from A to B or to the local coffee shop. Not very artsy though !
On the other-hand I doubt any of you here will be visiting any of my worlds so extreme accuracy is less of a priority and for all intensive purposes they are just decorations. That somewhat resemble maps!
What is required to define a map . The purpose (real/imaginary) the Goal(Real/imaginary) the information (real/imaginary) required to fulfill the goal. The larger the purpose and goal ,the more information that must be conveyed in some manner.
A photo or painting of your cat isn't a map unless of course you are a flea and it also conveys the quickest route to the richest blood sources.
Do maps need to be artsy ?? Does food need to be tasty ?? Lets face it not really ; BUT it is much more entertaining/enjoyable that way. As pointed out above. Certain artistic treatments(Although often done to death)(certain Fonts to remain Nameless) Add additional "Flavor" to the necessities. Sherlock Holmes could discern Volumes from the paper; font ; aging etc. Personally I find Atlas maps USEFUL but BORING. Purposeful but Flavorless. Still the serve their purpose well. I almost always post a back story with my maps. it helps me to convey the mood I am trying to get across in hopes someone will tell me if I did or didn't. It also helps me get into the mindset of the "Cartographer" and how would he/she map this area/object out using what techniques and tools and materials. Necessary ? NO !! Fun ?? YES !! There you have the whole mess ! Phew my hands are tired. So is my spell checker . Map what you feel, ask other if you are getting your "Flavor" across. And the techniques will come with time and guidance from all the folks here !
PS> My brother respects my maps for the work that goes into them but since they don't look like a map for an Edgar Rice Bourghes Tarzan novel he really doesn't get the Vibe !!