Quote Originally Posted by Dawnseeker View Post
Remember that gems are incredibly common. You certainly don't have to buy them. Most people would rather win something than earn something. Winning is exciting. If we changed it, it wouldn't be as exciting when you finally did hit 15.
Incredibly common? Tell that to someone farming them legitimately without the use of a bot or coining. with a setup of 4 lvl 5s at each city it takes 150+ days sending waves once per hour 14 hours a day to reach a 15 star set. needless to say I stopped at 13 and a half.

The real reason its based on chance is to get a player to try an upgrade they can't afford to have fail on hope and then when it inevitably does they coin to regain what they had.