So thoughts
Each plugin should specify its licence but typically they are so open you can modify and redistribute. The only fair limitation is to not pass one plugin off as someone else's with changes as this can undermine the authors version control. Bundled plugins have typically being distributed as editions but I see no reason not to bundle plugins perhaps in a json bundle. I think the key is to list and acknowledge what you have used and included if for no other reason than informing the user however I think a key approach is to respect others work.
If publishing a bundle modifications or additions that impact the core or another's plugin macro should be documented so no one seeks support from the author when its your mods breaking something.
When bundling others work unaltered check the source is documented so should an update be required say with a core update then people can source the latest version. The danger of a repackage can be components age.
Regards
Tony