One use is to have understanding of how viruses work, so that you can accurately predict spread. If we assume that SARS and MERS (both coronaviruses that seem nearly certain _not_ to have been made in labs) required a knowledge of how coronaviruses work, then a lab doing the general kind of work that was done in Wuhan is real.

For example, we already knew that the spike protein was critical in reproduction of the covid-19 virus, whereas we might not have known as much about that if we had no virology labs (I'm not an expert in the field, I might be wrong here).

But, for any particular line of research, your question is still a valid one. Is this particular research likely to have a payoff worth the (inevitably non-zero) risk? The issue is how (and who) to make that decision.