Japanese food culture
Why do people slurp noodles in Japan?
Because in Japan, slurping noodles is normal rather than automatically rude—and many people feel it helps them enjoy hot noodles and aroma.
From my Japanese perspective, the sound itself is not the point. Drawing noodles and air into the mouth can make the aroma feel more noticeable, in a way that reminds me of how air is used when tasting wine.
You do not have to slurp
It is perfectly fine to eat quietly. If you are outside Japan, I think it is sensible to follow the table manners of the place you are visiting rather than insisting on Japanese habits.
When you visit Japan
If you want to try slurping ramen or soba, you usually do not need to worry that the sound itself will offend people around you. Treat it as an option, not a rule.