I think this is a feature for stores implementing WiFi tracking systems, not a hindrance. If I own a store, I really want to understand traffic patterns. If I can do that without causing a privacy shitstorm, I think that's a benefit.
They can use their extensive existing network of closed circuit video cameras to identify traffic patterns. Unless they want to tie customers to profiles (e.g. MAC to a credit card transaction) the resulting data would be the same. Cameras are even better at this because it counts everyone, smartphone owning or not.
You can't understand patterns from random data. Am I missing something you're seeing?
They can still understand when anonymous shoppers arrive and when they leave. However, I think zaroth is underestimating how much more useful it is to track an individual shopper's visits over time.
If the devices now send a random address for each probe request, you can't even do that anymore... all you'll have is a database full of single requests for a ton of random macaddress
Traffic analysis and some statistical methods should give you a lot of interesting data. Yes it's not individualized long-term tracking, but you can figure out when and where people are visiting, and I think even tease out how long people spend at each point, even if the MAC is randomized for each request.