Using the raise_error matcher without specifying a particular error type is quite dangerous, as it swallows any sort of exception, including syntax errors and rspec expectation errors. It's hard for me to imagine a reasonable justification for the author of a test not caring at all what type of error is thrown; in my opinion it would be more helpful to users of rspec to be forced to think at least a little bit about what type of error they are expecting.

If there's no agreement on that, then at least perhaps it might be worth considering changing the default from Exception to StandardError.

For quick reference:
https://github.com/rspec/rspec-expectations/blob/master/lib/rspec/matchers/built_in/raise_error.rb#L11
https://github.com/rspec/rspec-expectations/blob/master/lib/rspec/matchers/built_in/raise_error.rb#L42-L49