I agree. The tyres are very affordabe (the size, I guess). However, it would be nice to see more choice. I'd like to put some stickier tyres on the car. When I had my Golf I had Fuzion X ZRi's (off-brand Bridgestones) that I really enjoyed. Different tyres can have a marked impact on a car's handling and performance.
Edit: On that note, there shouldn't be anything preventing other manufacturers to start making the size tyre except for the fact that there aren't many smarts yet and it probably isn't a profitable venture yet (unless Conti has patented the size, which would be a bit sketch). Once we see more cars, we should see more brands entering in as competition.