It's standard practice to monitor applications in an office in order to detect, diagnose, and fix issues within the network. Often, the goal is to fix the issue before an end user even experiences it, which could cause a bad perception of the company, lost profit, and lost time. That being said, there are many different ways that an application is monitored, and there are many facets to the environment of application servers. Proactive application monitoring tools are there to ensure issues or potential issues are cured before they have any real effect, but how do they work so well.
Another huge benefit is the fact that proactive application monitoring takes the spontaneity out of having to respond to alerts when an issue does arise. Instead, developers can focus on developing and taking care of the proactive needs on a routine basis. It's less distracting and more cost-effective.
When working in an office, you go into the environment assuming that a thing or two is going to go wrong here or there. The reason so many people like these tools, though, is because they're reliable. They've been tested and re-tested to ensure that they can handle a job of any size, so they'll never get overworked even when your applications do. This can be attributed, in part, to how they are developed (re: no code). The results produced are also very easy to understand, so anyone can take advantage of these tools.
Their comprehensive reporting skills collect data about application performance that can be used for the company's benefit. Even if apps are not down, per se, they could be running slowly enough as to cost the company money. Reporting from monitoring software will help developers to pinpoint what's going wrong and take care of it. They can also monitor the network to see if anyone is using too much bandwidth, et cetera.
And, of course, there is the benefit of cost. For every minute that your application is not running properly you're losing profits from use and giving customers a bad experience. Although, of course, there is an up-front cost associated with proactive application monitoring , it pays itself off in terms of time and money that would have been used to fix errors.