I think the problem is that people still assume that games are aimed at children, when the majority of iOS/Android apps are aimed at adults. For example, Candy Crush looks very cutesy and bright, but the vast majority of its players are in the 24 - 55 year old bracket. Same with Clash of Clans.
Free to play games (where they're free to download, but have IAPs) still cost money to develop, and the way companies recoup those costs are through the IAPs - they avoid issues with piracy and, if they're successful, can make more than if they'd followed the traditional business model of "make game, release at RRP, all content up front".
The problem is that, out of all the players that will download a F2P game, only 3-5% will monetise. So there's a lot of 'Whale' chasing - a whale being a gamer who is willing to invest large amounts of cash on the game. For example, the top Clash of Clans player has spent $7000 on gems. Something like the top 10% of players that do monetise are responsible for 50% of IAP income, hence why there's often 'whale chasing' (the £20+ IAPs).
The games are built around compulsion loops and various tactics to encourage people to continue to play, to monetise and getting the playerbase to promote their game (seen more in Facebook games), hooking in more people through social obligation.
I think it's more the responsibility of the parent to ensure the security of their phone or tablet, rather than expecting the manufacturers to completely child-proof a device that isn't aimed at kids. Same with PCs for that matter, I still remember that toddler who bought a JCB off eBay. I guess we'll see less of these stories as people become tech savvy (plus the Office of Fair Trading is currently investigating in-app purchases! :P)