Also that is good in theory, but in practice new software comes with new features and new unknown bugs, while old software has old known bugs patched.
New releases also ship with new features that change behavior or even interfaces. An Enterprise distribution is supposed to keep behavior and interfaces stable and trusted. So shipping latest software goes against that need that business have. The last thing you want is that a kernel update suddenly impacts performance/behavior and outdo any performance tweaks you prepared and implemented on your 400 servers before.
Of course if you don't have that need, you may as well find yourself using a bleeding edge distribution, or one that is more often updated. But that is not what enterprises desire in general. It's a balance of what you think is important, and that might as well be different for different users.
If a typical hardware lifecycle is about 4 years, and commercial software is adapted to run on a new OS release only after 18 months of general availability, you cannot expect a company to standardize on new OS releases every 6 or 12 months. The preparation and migration of your production environment simply is too time-consuming (and too costly)...