I've heard the same about wasabi killing the bacteria. that was the reason back in the day when sushi was 'developed' (lack of a better word?).. it was cheap and easy street food for workers (kinda how 'hoagie' or 'submarine' sandwiches were 'developed' for the USS Hoag in a dock in Baltimore.. cheap and easy food to feed workers), but the fish wouldn't always be fresh so they used wasabi to kill bacteria and stuff, not for flavor.
I dunno if either are true. lol. but I don't ever eat the ginger (pickled ginger).
I think the real old school sushi they used fermented fish and the rice was used more as a container than anything and they'd toss that shit before eating it. People started changing things up, putting vinegar in with the rice and other veggies and dried preserves like nori (seaweed), etc. Over time it continued to evolve into what we know now.
I don't know if the wasabi is really enough to kill bacteria considering how you don't smother it with wasabi, but it's good shit nonetheless. Pickled ginger is good too. I'm amazed that you don't like it. It really cleanses the palate and opens up your nasal passage. I usually eat a solid metric fuckload of ginger along with my sushi. I've got jars of it in the fridge and if I've got a stuffed nose I'll just eat something Asian tasting and eat a few bites of ginger along with it. I cook with a lot of ginger too. It's unbelievably healthy and goes well with tons of different meats and veggies. I like Szechuan green beans with a little ginger and sesame oil. Always impresses the fuck out of dinner guests but is so simple a retard can make it. Very healthy, only fibrous carbs and kills the munchies.