Personalization became a hugely successful business practice about mid-way through my high school career. I remember this because Nike convinced me that having my name and softball number embroidered into my cleats that already featured a non-typical color combination in order to reflect my school colors - was worth the small $30-$40 fee, plus the cost of the shoes and shipping. It was new and unique and totally played into my inclination to be the first to try something, anything.
Six years later, it seems the tables have turned, though in a gradual, slow manner. McDonald's will take your coffee order AND "fix" it the way you like it -- one cream, one sugar and so on. Dell boasts its ability to literally build your computer the way you want it, but their catalogs overwhelmingly advertise packages that are pre-determined. And Einstein's Bagels, the example I personally very strongly dislike, puts the peanut butter on your toasted bagel for you; they charge $1.25 for the peanut butter and apply enough of the spread to satisfy a small army. Although I'm sure the thought is in line with a full-service mentality -- a convenience factor when many things are no longer convenient -- I would rather prepare my own coffee, choose elements for my computer that actually apply to me, and decide for myself how much peanut butter I really want on my bagel.
Starbucks has personalization down to a science, and it works. There is a definite trend in having a longer, more demanding order paralleled with being a serious Starbucks connoisseur. This is an interesting factor since, logically, a serious coffee drinker should order the daily extra bold brew and drink it black, end of story. But they've created a lifestyle, and it suits the typical Starbucks drinker because they're privileged and accustomed to being catered to.
I don't think there is a right or wrong in choosing convenience or personalization, rather it's circumstantial and more importantly audience-specific. If the product allows, the best solution is to give an option: let the customer decide whether they're in a hurry or would like to spend the extra time being catered to.