I’m not opposed to using the smile, but I am playing devils advocate, and I am saying that “just a smile” is not enough. Read my posts in regards to the currency symbol (particularly Currency Symbol [ ɠ / ꞡ / ǥ / other ] #BS - #66 by shush). My position is that the symbol shown includes both the letter G and a smile in a unique way that also loosely resembles an existing currency symbol. I believe that the symbol makes a lot of sense when we consider this.
However, I’ll consider a smile as the concept behind the brand and currency symbol exclusively. The only immediate objection is that the brand doesn’t command itself as a currency. Going with the pre-existing notions of what a currency should look like by society would benefit Grin’s brand in the short term. In the long run, future generations might associate a smile with money more than $, £, or €, but I’d argue that it’d be difficult to make current generations associate ツ with money.
Aside, allow me to ask you this: How could we design ツ to more closely resemble a currency symbol for a future official Unicode character?