Hopefully this doesn't fall under "opinion" but I believe this will help alleviate some questions on mashing/fermentation techniques. I guess you could break this question into parts. Also the term "drinkable" is assuming the beer is without off-flavors:
Are the terms "dry" and "drinkable" synonymous? My initial answer would be no, since I've had Imperial Stouts that I'd consider more drinkable (not to be mistaken with sessionable) than a dry-stout, say Guinness. Then I've had stouts with lots of residual sweetness that were good, just more of a sipping beer. Although, a "bone dry" beer may not be considered drinkable either. So without answering my own question, I guess it's safe to say drinkable is more related to residual sweetness/alcohol perception?
Are the terms "dry" and "low FG" synonymous? Again, a dry beer tends to be low FG but not necessarily the other way around? Can you have a dry beer that was mashed at the higher temp range.. if so what type of body would you expect? I'll use Duvel and Jolly Pumpkin as an example. Both produce great beers that favor the dry side, but certainly do not lack in body. I know Duvel finishes low, Jolly Pumpkin it depends on the beer.. but a good amount finish low.
I see these terms being tossed around a lot, it would be good to back them up with some facts.