Bob Sutton posts about why generalists are less grumpy than specialists. The answer is somewhat intuitive but worth remembering: when your eggs are in more baskets you mitigate the risk of being crushed when any one basket blows up. He quotes:
Generalists, people with moderately strong attachments to many ideas, should be hard to interrupt, and once interrupted, should have weaker, shorter negative reactions since they have alternative paths to realize their plans. Specialists, people with stronger attachments to fewer ideas, should be easier to interrupt, and once interrupted, should have stronger, more sustained negative reactions because they have fewer alternative pathways to realize their plans. Generalists should be the the upbeat, positive people in the profession while specialists should be their grouchy, negative counterparts (page 526).
The citation is from organizational theorist Karl Weick, who has also argued that the right attitude for learning and creativity is to "argue as if you are right and listen as if you are wrong."