The tubes on the overflow pipes allow the gas coming out to run down and not make a mess. If the needle valves are not sealing well, you can get gas dumping out which will drip down onto the bike.
The hoses on the vent pipes keep junk from getting in the carbs.
Best to have the tubes and route them away from the exhaust and rear wheel. If you get a leak you want the fuel to stay away from a heat source and your back tire.
