…your website never has any content changes.
If you have a ten page website and around three webmaster edits a year.
If your site content changes are always done speedily, correctly, and very cheaply.
Or if, on the other hand, you don’t care that your last content edit took two months of badgering the webmaster.
If you are an enthusiastic amateur, and enjoy the hours of work involved with regular content changes.
If you are a web publisher – because you’d put yourself out of a job.
If you are a webmaster who likes doing text edits. Oh yes, what fun.
If you just don’t believe the notion that 99% of content changes are actually possible using your browser to edit the content online, whenever you feel like doing it, and think this must be a myth or something.
If you think ASP-.NET semi-dynamic solutions hosted on an MS server, with an extended start-up phase and regular developer costs, are a good alternative to a stable, secure, virtually out-of-the-box CMS/ LAMP solution.
If you must have the ultimate designer-look website, with only a few pages, mainly based on graphics, and selling or featuring graphic-based products.
If you don’t actually like the businesslike look of a standard CMS template.
If your site is basically a blog, a wiki, or something else with a dynamic engine anyway.
If you are a hand coder and still love it dearly after all these years.
If you hate XML for some reason.
If you sincerely believe all web pages should look like a Notepad page, or a page from a Quake clan site.
If your idea of a nice look is an artwork layout by one of those people who exhibit regularly in the Tate Gallery.
If you think all user-interaction is the work of the devil.
If your online store is so big and successful that it needs no content pages whatsoever to get top SERP positions.
If you thoroughly dislike the idea of being able to add new major functionality to your site with a half-hour module addition.
If you love Dreamweaver more than life itself, and can’t bear the idea of relegating it to menial tasks such as template authoring, page validation etc.
If you think all pages should be built with Dreamweaver or FrontPage regardless, and actually like taking an hour or three to work up a couple of simple pages.
If you run a big department of web publishers, site maintainers, and webmasters that would get the chop if the boss found out about CMS.
If you run a web design agency that hasn’t heard of CMS yet.
If you think Coldfusion is the answer to all and every web design issue.
If you think the idea of thousands of plugins being available for just one CMS simply means it must be badly coded to start with.
If the idea of being able to change a website’s entire look with a 5-minute template changeover seems pointless to you.
If being able to use half a dozen different templates on one site, on different pages, all at the same time, would be wasted on you.
If the task of rebuilding half the site’s navigation when a page is added or deleted actually fills you with delight.
If your server has no PHP or mySQL on it, or is a five year old IIS job.
If you look forward to the long job of totally rebuilding the site navigation when you add or delete a directory.
If you prefer to build the entire site in Flash, then leave it like that for ever.
If you don't care that the PHP or ASP solutions you build for clients take 3 months to roll out.
If you look forward to major site redesigns with joy.
If your business is based on client fees for building new pages, changing content, and page redesigns - since you'd be out of a job if they had a CMS.
Seriously though, many websites don’t need CMS, for good reasons; but installing one usually solves a lot of problems and worries. Nothing in this world is perfect, it’s true; so of course there are drawbacks. These are normally short-term issues though, such as the learning curve for the sysadmin, and the slightly easier one for the end-users (since they can now do all their own content edits via a browser, should they wish); and also migration issues of course. In the long term, the vast majority of users are not only glad they changed over, but also wonder how they coped before.
From our point of view, we prefer the more interesting technical issues that come with CMS over those that attend flat sites. It's true that search engine optimising some CMS sites is not the easiest of tasks; but it will make a good site much better. From the owner's point of view, time saved on content changes at our end can be devoted to SEO, which is a lot more cost-effective.