While they are on my mind

Giving hosts the ability to postpone races is something we could do. But it's not as simple as just throwing it in, we'll need to give serious consideration to the consequences, and any limits we'll need to enforce on that power to ensure it isn't abused or doesn't disgruntle other users. The obvious choice then is to have a poll system, but then you're talking about an integrated poll/race postpone system that would need to be built from scratch. And then what seemed like a small idea starts to become a big development project.

The ability to restart a race is off the cards because that would be so easy to abuse. Someone might just keep restarting a race until they get the perfect outcome.

Again having custom schedules and more tracks is something we'd love to have, but it's a huge development task. I'd need to add a calendar building tool, and that has to have countless checks and balances to make sure the right number of races are entered, races not entered twice, sync everything with the right schedule and so on. In many ways the current 17 race schedule is hard-coded in to areas of the game, and all of those areas would need to be updated too. But this is something I'm certain we'll do eventually, when we have enough spare capacity for it.