We all started as crypto newbz by just buying a small amount. This is perfect for onboarding in my opinion because it is so easy.
Yes, more experienced users probably have a cheaper way of buying cryptos. But that is not the point. The crypto crowd is still quite small and we have tons of work to do. But seeing theese ATMs everywhere, it will trigger interest in people who are inexperienced with new technologies.
I understand your security concerns though, because there is no 2FA for email accounts. It could be stolen via hacking or keylogging. But they don't supports transaction bigger than 500$ anyway. Maybe they will find a way in the future to make it as secure as 2FA on exchanges.