TERs are necessary. All Test Case execution happens in the context of a TER. It's a central artifact of RQM execution. Not only does it allow you to show the Result History, but it also ties into reporting. Several of the reports are centered around TER (e.g. Execution Status using TER count).

Even if you only use a single test environment, you would likely want to use TERs to capture the planning information for your test execution. That is, which Test Plan and which milestone you plan to execute a given test case.

There are several ways TERs can be created. If you just hit the run button at the top of the test case editor, then the run dialog will give you the option to create a new TER. You don't even have to specify the test environment. That's a shortcut for folks that think creating TERs individually or via the wizard is too much trouble. However using this approach doesn't give you any of the planning benefits of reporting.