Tag-based applications are becoming the selected platform of what Tim O'Reilly coined Web 2.0: "web applications that facilitate participatory information sharing, interoperability, user-centered design, and collaboration on the World Wide Web" (source: http://en.wikipedia.org/wiki/Web_2.0). Companies are reacting to this new reality and learning about the best way to deal with this type of technology.
Of course IT still has responsibilities on the site, and do have to participate in the tag deployment process. But instead of having to learn, implement, and validate the installment process for each tag-based system - they can focus their resources within the TMS workflow for issues such as performance and compatibility.
Many of the tags implemented on websites are "conversion" tags that measure the efficiency of online campaigns (also known as post-click tags). These tags tie in conversion data back to marketing spend to analyze ROI. This is great, but if you are working with various marketing efforts, you are probably crediting some sources more than once and not having a holistic view of the actual return on investment. Use a TMS system to help gauge the participation of each effort in the actual conversion.
The real benefit of a TMS to the analytics industry is the capability to dwell in and interact with specific behaviors observed in a web analytics platform. There are various tools that allow websites to really gauge user behavior and reactions. These tools include real-time heatmaps (such as CrazyEgg or PClicks) or feedback/survey apps (such as KissInsights). These tools can be very useful to investigate the root cause of a specific behavior. A TMS allows instant implementation of systems like these, while without a TMS - these tools would have to be implemented by IT.
Ultimately, a TMS allows a website to renew and to change, which in my dictionary is called innovation. Giving the marketing department the capability to deploy a new application on a website within minutes changes the game of what a website is and what it can do for your company.
Our take on how to really promote innovation is to create an open marketplace for website apps. We just launched SiteApps.com - which is a TMS with a twist: not only can you manage your tag-based applications, but you have a marketplace where any developer worldwide can submit an application that can be used on your website.