Despite (another) of Agent's unmoderated allowed arrogance, he's right. You aren't forced to complete a set of tasks. You won't lose anything if you don't (differently of when DC was released in BETA, dragging you one step back for each you accepted and didn't finish).
And for this set, you're indeed complaining without reason. Really bothersome tasks are "Finish 90 productions of 5 minutes". Even with 12 Blacksmiths (that's the max I can afford with my limited space), it's a relatively long time to just sit and watch smoking chimneys (or having the game sucking memory in a backgrounded tab).
But I have to agree that the rewards are very unbalanced. I'm not saying we should have a much higher chance to get the top prize, but the lower ones have a much higher chance which almost defeats any of the intermediary chances listed.