It's not about making the bar just taste good. It's also about providing QUALITY carbs instead of just straight up sugar.
Let's be realistic here, PLENTY of folks whom consume MANY Quest bars whom actually do need extra calories and carbs. MANY. There's a LARGE customer base whom are not cutting and would do well with more carbs and what not in their bars. They are consuming plenty of Quest bars, the main reason? Mainly due to brand recognition. Plain and simple. At this point, it's the brand that is the main selling point for the products, not necessarily the products themselves. For goodness sakes, go walk into a GNC, they essentially no longer carry any other bars apart from chitty house branded ones and the rest being pretty much all Quest.
What would I expect from a Quest High Carbs bar? QUALITY INGREDIENTS. It's not that easy to find a high carb bar with excellent quality ingredients and protein sources. There's plenty of high CALORIES bars but a large portion of their calories are coming from fat sources, not necessarily carbs. Even Fit Crunch which is high calories, there's barely any carbs in those, they are mainly sugar alcohols.