A good point! Low fee's are only low so long as the price of the coin is low.

Back in 2015, I could send a Bitcoin transaction with a fee of 0.0005, which was a few cents. That was a low fee. You can still send with that same fee and it still works (sometimes), but now that's $7. That's also only accounting for that fee in USD (my local currency), not to mention when you add another dimension of additional non-USD currencies and their relative values, it gets way more complicated and sometimes expensive.

No fee's was one of the reasons I have been a big fan of Steem, and is one of the reasons I'm also a fan of XRB.