It's limited mainly for simplicity. Since it's intended to be a cheap and quick answer, we figured $5 and 50 questions seemed reasonable for most. Perhaps we can keep the standard, advertised solution at 50 for $5 but when you buy offer the option to upgrade to more questions.
If you go that route, make sure to make it more discoverable. If people write off your product because they need more responses, they're never going to figure out that they could get more.
