Feature buys allow gamblers to set off a slot's bonus mode by paying a certain amount (oftentimes 100 times the wager amount) without actually playing the game to trigger it. While the instant gratification is nice, the risk to gamblers is a lot higher, and the regulator is worried about the potential harm that could be caused.
The regulator said that every year between 250-650 people kill themselves due to gambling-related problems. Needless to say, the topic of problem betting is a big deal within the country, as more than $18 billion is spent on gambling on the country. The UKGC has worked to change betting laws in the UK, as they've successfully gotten FOBT max bets lowered from £100 to £2.