When you install ESXi 5.x from vmware you don’t have all the plug-ins or modules that a vendor customized ESX images has. Why you ask? well you might want to monitor your ESX host with HP insight manager, IBM System Director or other management software. Or want to update your drivers and firmware with update software of the vendor, with this customized images of the vendor yo don’t need to install de additional plug-ins.

here are some links to the vendors i use the most ( at the time of writing ESXi 5.5 update 1 was out)

there might be other images but these are the most used i think

hope this helps