I'm not quite sure why an upright 4 Cups is seen so negatively, to me it seems like super stable emotional stuff, just fine with where they are at and not really open to what else is offered or available. There is something supportive, alive and growing at their back if you look at an RWS card, comfortably leaning on the tree that shades and protects them. it may not be so ho-hum as humming and at peace with themselves and the universe that they don't need outside stimulation or extra excitement to feel just fine.... although the facial expression does look like they are either on downers or stoned out of their mind.
Maybe that is boring, too laid back for words... so reversed is taking that to further extremes...emptiness, depression, total lack of motivation, feeling flat, too self absorbed to be interested in anything, letting opportunities pass and feeling unfulfilled, total rejection.