[bmm6o]

Even if you are adding features, some software products are such that customers simply can't/won't upgrade at a pace of more than a few times a year (if that). Anything mission critical will need to go through validation, acceptance testing, you'll want to check that integrations with other products are unaffected, etc. Especially if the organization is understaffed in the IT department, then these sorts of upgrades can easily lose priority to the 100 other things on their plates.