Two things:
* Long term commercial support, underpinned with (legal) contracts. For an enterprise it is extremely important to be able to convince clients that in case of outage all precautions reasonably possible were taken to prevent or at least minimize impact. If not you will probably be held responsible for losses (which can be huge), if necessary ordered by court. Remember that in enterprise market the stakes are high and no-one will hesitate to bring in their lawyers. In the end, a client's only interest is its own share price, not yours as provider / hosting company.
* Only proven technology in stable releases (often several stable releases behind current with back ported security patches).
And often: development tools (like header files and compilers) not installed by default. Those are for test/dev boxes, not for enterprise production.