Adding any deterrent (more, better, larger, etc.) seems to me like a "chicken or the egg" game. ATMs get stronger security, scammers develop better methods to skim. Skimmers improve, ATMs get better security. It becomes a viscous circle of who can outwit the other for a longer time and prove more successful.

Personally, I am more interested in improving security via credit card chips or contactless payment (cards or phones). Chips alone would heavily improve security due to the inherent cost (hopefully) of cracking the chip's data.