Well, although FlexNet is coming, in my opinion, FlexLM has a long way to go. So I believe it doesn't make much sense to study the FlexNet for now.
In most cases, it is not the better performance, better security, but the cost of the transition.
A typical cycle of the business is, develop and maintain, then over again. The company will protect their investment in the current product, also the maintenance cost will be a great consideration.
We had an example here, one company upgraded there Flexlm license format, and that result in two version of the product had to be maintained in parallel, which is another cost for them, also, their customer not happy. Not every custom want the latest software, some of them just stick at the old version of the software which they had been using for years. What shall we do about that, the customer is the god.