It would be nice to use Readers instead of InputStreams for templates.
Velocity is all about text-based rendering, so the templates are certainly going to be text-based. Using a Reader allows individual readers to determine the character encoding if necessary (say, from a database) and not have another component second-guess them.
Of course, this is a serious change to the API. We could possible re-implement getResourceStream to read a Reader and provide bytes as backward-compatibility with older client code, but since we're going to 2.0, this would be the time to make breaking changes to the API.