Today, one can find a framework for just about any language, to suit just about any project. Most modern frameworks are fairly robust (generally speaking), with hour upon hour of testing, peer reviewed code, and great extensibility.
However, I think there is a downside to ANY framework in that programmers, as a community, may become so reliant upon their chosen frameworks that they no longer understand the underlying workings, or in the case of newer programmers, never learn the underlying workings to begin with. It is easy to become specialized to a degree that you are no longer a 'PHP programmer' (for example), but a "Drupal programmer", to the exclusion of anything else.
Who cares, right? We have the framework! We don't need to know how to "do it by hand"! Right?
The result of this loss of basic skills (sometimes to the extent that programmers who don't use frameworks are viewed as "outdated") is that it becomes common practice to use a framework where it is not required or appropriate. The features the framework facilitates wind up confused with what the base language is capable of. Developers start using frameworks to accomplish even the most basic of tasks, so that what once was considered a rudimentary process now involves large libraries with their own quirks, bugs, and dependencies. What was once accomplished in 20 lines is now accomplished by including a 20,000 line framework AND writing 20 lines to use the framework.
Conversely, one does not want to reinvent the wheel. If I'm writing code to accomplish some basic, common little task, I might feel like I am wasting my time when I know that framework XYZ offers all the features I am after, and a whole lot more. The "whole lot more" part still has me worried, but it doesn't seem that many even consider it anymore.
There has to be a good metric to determine when it is appropriate to use a framework. What do you consider the threshold to be, how do you decide when to use a framework, or, when not.