In general, it is important to include details in your writing to give your ideas more impact and make your writing more interesting. This is especially important for personal narratives and persuasive essays. (Actually, it's hard to think of a type of writing, aside from perhaps a research paper, that wouldn't benefit from ample but relevant detail).
Why are details so important? For one, your goal as a writer is to create a vivid image in your reader's mind so that your main points are made more forcefully. It is hard to do this with vague information.
Compare the following two samples of writing to see the difference:
(1) Although college is important for many people, it is not absolutely vital in all cases to become success or to reach one's goals. Bill Gates is an excellent example of someone who is not just successful, but also highly accomplished and influential in his field of work. Bill Gates famously dropped out of Harvard College, one of the most prestigious universities on the planet, to found a little software company called Microsoft in the 1970s. At one point, with a fortune of over $40 billion, Gates was the wealthiest human alive. While one could argue that Harvard played a pivotal role in Gates' later success, it is self-evident that the entire four-year undergraduate program at Harvard College was not necessary for Bill Gates.
Okay, now let's look at the same ideas expressed with less detail:
(2) It is not important to complete college in order to be successful. Take Bill Gates as an example. He didn't finish college, and now he is extremely wealthy, even though he doesn't have a college degree. Bill Gates had what it took to be successful, and he didn't need college at all.
Which sounds better to you? (1) of course! Why? Because it has more detail and is more specific. Try to do the same in your own writing as well.