Virtually every decision I make is based on my personal experience - I don't know how e.g. Java would solve a problem, so I can't recommend it. It's as much about individual knowledge as personal beliefs. For example, I happen to know that awk makes a very good job of splitting and printing fields separated by whitespace; I know how it works, and I'm comfortable using it. Other people, unlike me, may not have learnt awk before moving on to Perl, and therefore might advocate a Perl solution. Which one works better depends on the situation.

In my job, I've got almost free reign over the language I choose to write (current project here) in. I almost always choose Perl out of personal preference.

The key is being able to accept that the hammer you're wielding now might not fit the nail in question, and the only way to make sensible decisions about that is knowing enough to compare hammers. Learning Java will allow you to judge the relative merits of Java and Perl, and decide which is the better tool for the job.

Whether you've done wrong by recommending Java is probably up to your employer. Either way, your ability to do your job depends on how well informed you are, so I'd argue that learning another language (where time is not paramount) can only make you a better programmer.