For years, SQL Server included a complete set of add-ons with the main product. We got SSIS, SSRS, and more as part of an integrated installation. This also included things like Books Online and various tools, such as Profiler, bcp, and Management Studio (Enterprise Manager in earlier versions). Over the years, the number of tools has grown, but there has also been work to decouple some of these items from the installation media and allow them to be upgraded more rapidly. Books Online was the first to separate, though not without some pain for users that struggled to install the local help files.
Last year SSMS was decoupled from SQL Server, which I think is a great idea. The tools team at Microsoft moved to their own release schedule, getting SSMS onto the Visual Studio 2015 platform. This wasn't without some pain, and there were definitely some releases with issues, but overall the process has smoothed out and I've appreciated the updates. This separation has allowed new features to be added to the product without waiting for a new release. If you watch the changelog, you will see quite a few improvements and fixes being released, along with enhancements. SSMS is also free to download and install on workstations without SQL Server.
However, if you examine the installation for SQL Server, there are plenty of other products that could benefit from being decoupled. While bcp and sqlcmd don't change much, why are they a part of the server platform? These tools, along with others, are really client side tools, and would benefit from their own release cycles. Whether or not teams do significant work, or even if they only release updates when a new version of SQL Server comes out, having them as a separate set of tools, with a separate installer, means that fixes and enhancements could be sent out if there are issues. This seems especially important for security updates, which might be needed. In addition, maybe this would actually get teams to view any separate tools as worthy of new functionality if they see an opportunity.
I'd actually love to see some integrated installer for the SQL tools that would allow me to download and update them each as needed. Let me know when SSMS is out of date, along with any updates for sqlcmd, sqlmaint, tablediff, and other tools. They might not change often, but I'd rather not have to run the SQL Server installer for a CU on all my client workstations. Let me update those tools as needed, if there are changes or improvements.