The limit was 5, and was already raised twice. At 5, people said 10, at 10, people said 15.

At the end of the day, you'll always want more - so what you have to ask is if there's a structural reason why you want more. Should you be giving out more than 15 reps a day? Perhaps in extraordinary circumstances you happen to come upon a profoundly intellectual thread where 20 successive posters deserve rep. But that will be the exception, not the rule.

The fact that you've only just run into the 15 reps a day situation is proof enough that even you aren't that limited by it.