Individual opinion incoming:
A) Aromatics, particularly many of the ones that come wet and/or drenched in PG, are harder to smoke. They're more difficult to light and keep lit, and tend to smoke hot, wet and steamy.
B) Too much added flavoring hides true tobacco flavor. Aromatics, when done well, harmonize the natural flavors of the tobacco with the adding toppings. Over-sauced aros tend to leave me dissatisfied with the smoke because they end up just tasting like sweetened, creamy air at best, and at worst, a very artificial taste (I'm looking at you, Captain Black Cherry/Grape).
C) Some people are just biased against aromatics. I probably am a bit biased, but I do enjoy lighter aros where the flavor toppings don't totally dominate the blend and the tobacco is dry enough or can dry out to a proper level of moisture for smoking (enough PG and it simply won't dry out unless microwaved or something).