Offhand, two reasons why pastors should listen to other pastors spring to mind.
The first is quickly stated: pastors need feeding, too. It is nourishing to study, to pray, to meditate, to prepare and deliver sermons. But not nourishing in the same way as hearing a brother proclaim the results of his own study and prayerful reflection. "Ministers" need to be ministered to.
The second I might call fear of the Rush Limbaugh effect.
Ten-plus years ago, my schedule was such that I listened to Limbaugh faithfully every day. He helped me keep my sanity during the dark days of The Nameless One's reign of error (1993-2001). This post isn't about Limbaugh per se; my summary statement is that he is a remarkably talented man, and a flawed one; he has about the wisdom one might be expected to amass outside of Christ.
But here's the point:
On rare occasion I now tune into Limbaugh, and even brief visits show that he has not changed nor grown a smidgen in over a decade. I don't refer to his not having "grown" in his viewpoint. I mean that he is using the very exact same schtick, down to the exact same phrases, words, jokes, puns, expressions. He is stale and stuck in his own past.
Why is this? It isn't that he isn't bright. It is, I think, that Rush has painted himself into a corner. He loudly and proudly proclaimed that he never listened to other hosts. He has no guests (with some exceptions). The show is all about him, him, him. He doesn't do interviews for the most part, doesn't put himself into situations he doesn't tightly control.
And so Limbaugh has, in my opinion, stagnated. His pose of arrogance is a bit more than a pose.
Now for a pastor who, unlike Limbaugh (to all the evidence I've seen), accepts warnings such as Proverbs 12:1 ("Whoever loves discipline loves knowledge, but he who hates reproof is stupid"), and 25:12 ("Like a gold ring or an ornament of gold is a wise reprover to a listening ear"), and 18:1 ("Whoever isolates himself seeks his own desire; he breaks out against all sound judgment"), and 18:2 ("A fool takes no pleasure in understanding, but only in expressing his opinion"), and 18:17 ("The one who states his case first seems right, until the other comes and examines him") — for such a pastor, I say, to isolate himself, and listen only to himself, and hear no living voice... well, to me it is folly.
A pastor should always be eager to grow and to hone the gifts God has given him (1 Timothy 4:15; 2 Timoth 1:6). One way is to seek out the ministry of other pastors, and not only the dead ones.
Thank God, then, that the Internet makes it so easy to listen to some of the godly greats of our day.
There is a down-side though. I plan to talk about it a bit in a subsequent post, when I talk about that darned Phil Johnson.