A quick Google search on "resume templates" turns up over a million hits, so it's no wonder that many job seekers are researching and then using templates when trying to put their own resumes together. Templates can be great for anyone who lacks confidence in their own design skills.
A template can also be a trap.
Some job seekers are fresh out of school and looking for their first industry job, while others may have thirty years of experience working for several employers. No two job seekers are the same. They have different employment histories, education, skills, certifications, etc., and all with varying degrees of value to a potential new employer.
What typically happens is that someone researching templates has a love at first sight moment with an attractive template without giving consideration for whether that template is a fit for their own content. The writer then tries to incorporate their content into this set framework. It's the equivalent of finding a really nice suit and buying it before even considering that it might not be the right size.
The end result is often a resume that is ineffective. Sometimes this is due to being afforded a limited space for the most valuable asset (usually the experience section) due to other areas being oversized (awards is a common one).
Other times it's because the template includes large areas of wasted space, such as bar charts that allow writers to rate themselves in a skill with a handy visual guide. Saying you are 7 out of 10 in JavaScript means nothing to anybody, so don't bother with these massive space-wasting images.
If you do choose to use a template, try to make sure it follows these guidelines:
Is it simple? Does the template make the content easier to read, and make your resume's sections easier to find?
Is it distracting? Is the template so highly visual that it takes attention away from your content? You need to be the star of your own resume.
Is it ordered properly (or customizable)? You want the reader to quickly see your most valuable assets first. If the template's structure doesn't allow you to lead with your best material, it's not serving you.