All of the breakers are there in one place so it's easy to turn things off there instead of wandering around the RV finding switches. It's also way easier when it comes to restoring all those switches to their "normal" condition. Lastly, the breaker is the onIy place you can turn the converter off.
Let's talk about the converter a bit. Besides the AC, that's really the one "appliance" you'll probably want to run off of the generator (to charge the batteries). It will draw a lot of amps when it's first started (since the battery is low), but after a fairly short time, as the battery comes up to voltage, the converter draw will fall off dramatically. (In my RV if falls from about 18 amps to 2 amps.)
If you have a surge protector or other current meter, or your generator has a meter, you could start out by turning on the converter breaker first. Run the generator with just that until you see the current drop way down and THEN turn on the AC. That way you can run the two appliances you really need. (You might have to turn the converter off briefly when you start the AC, but maybe not.)