Your question reminds me of the comment by the emperor in the film Amadeus. Here the emperor proclaims that one of Mozart's compositions has "too many notes". You have to be careful, though, with generalizing here. A great piece of art can have many notes as exemplified by the musical example above. In gastronomy: Think of the spice mixes in indian cuisine. They may contain dozens of spices. Leaving one out would destroy the balance. The same is said about the great works of Mozart.

The parallel between music and gastronomy is an interesting one. Herve This and Pierre Gagnaire are exploring the technical, artistic and divine (= love) aspect of gastronomy.

The parallel between the music and cuisine is interesting. Here a personal array of parallels between music and culinary artistry:

note = flavor
chord = flavors acting together
length of the note = flavor endurance
melody = sequence of events after bite or sip: head note, middle, tail
volume (pp, p, mf, f, ff) = intensity of flavor
rithm = repeating sequence (sip of wine - bite of meat - bite of carrot - sip of wine - ....)
parts of a symphony = courses in a meal
composer = creative - skilled chef
musician = skilled - creative chef

So the question can we define where one starts to have "too many notes" is a complicated one. Simplicity is, however, to my opinion always the best start. The more notes you use the more carefull you must be. The purpose of using many notes could be to achieve an effect of an entire new sensation, the birth of a new simple (!) and enchanting melody.

Now a question: If you think of your favorite song or piece of music, what meal or dish would correspond to it ?