This is about producing a minimum viable product for MediaUploader, so that the first version of it can be released.
The target MW version is 1.37, supporting 1.35 LTS would require too much effort and slow down development. We can re-evaluate the viability of supporting LTS releases when 1.39 comes out.
The first release will not include any groundbreaking UI changes, but it will introduce many configuration and internals changes. Backwards compatibility with UploadWizard will probably be limited and changes to config may be required in some cases when upgrading. Future releases should maintain sensible compatibility with this initial release.