To me I thought the same for a long time, until I realized things like soda had completely nuked my taste buds. After cutting out soda and other insanely high in sugar things a lot more started tasting better, and la croix now has a ton of flavor.
I'm sure that's probably true for many people, but also some people just don't vibe with seltzers. I quit drinking everything but water and black coffee a few years back due to kidney stones and I still can't stand lightly flavored seltzers.
Plug your nose and most things taste bland lol, and Iโm pretty sure they have flavor to them. Regardless, what difference would it make if the effect is the same?
If you have a weak sense of smell then you can't taste them at all. I can taste most things fine though (la croix excluded) without them tasting bland. Smell definitely adds to flavoring but it's not like it's the only thing responsible for how you taste food/drinks.