Say you're the president of Elbonia, and you get a report that an unidentified aircraft is in your airspace.

Without a human pilot in a fast jet, how do you get up there to take a closer look at the situation to decide what to do?

Modern warfare is limited in nature, with rules of engagement, etc.

Iran just shot down an airliner because they had poor ROE and control of their systems.

Just because something looks like a threat on sensors does not mean it is a threat. It could be that natural phenomena are masking things. It could be a ruse, such as an adversary is disguising a civilian aircraft to look military, or vice versa.

This result with dogfighting is interesting, but is only a very small part of what fast jets are useful for.