Welcome to the forum.
With a false bottom in the kettle, you could use the kettle as a mash-lauter tun for all grain brewing. You could also use it (as I do) for straining the hops on the way to the fermenter.
As I'm sure you realize is useless without a spigot.
The spigot is useful for draining hot wort from the kettle, where the heat of the wort could damage a plastic siphon. If you cool wort in the kettle, you can use a plastic siphon. About the only time you want to drain hot wort from the kettle, is when you are using a counterflow wort chiller, and if you do have a counterflow chiller and no spigot, you can use a metal siphon tube.
Hope this helps.