I use Bundler for all my application projects. Fortunately, nothing about RVM forces you to use gemsets. I use gemsets for scenarios where I'm writing code that will not run within an 'application'.
Ruby is my go to language for damn near everything. I use it for working with log files, parsing Excel documents & performing analysis, system administration, you name it. Many of these scripts are one-offs that reside in '~/bin'. RVM allows you to do something like this in your shebang:
#!/usr/bin/env ruby-1.9.2-p290@vqm-analysis
That's the first line in a shell script that I wrote to collect examples of bad calls in a csv file output from an AdTran 900-series VoIP gateway. The CSV file contains about 30 columns of data related to the quality of VoIP calls. I have a collection of five or six scripts that use that gemset, but they're not really an application. They just run from '~/bin', so using bundler isn't really practical. I could wrap them up in a gem and make them a proper application, but this is scripting. Simply using RVM + gemsets saves me a lot of time.
My point is that gemsets may or may not have any utility for you, but it's narrow minded to assume that they have no utility for everyone.
