I suggest anyone interested in creating mods read the Fallout 4 EULA posted on Steam.
A small section is:
"All Customized Game Materials created by you are exclusively owned by LICENSOR and/or its licensors (as the case may be) and you hereby transfer, assign and convey to LICENSOR all right, title and interest in and to the Customized Game Materials and LICENSOR and its permitted licensors may use any Customized Game Materials made publicly available to you for any purpose whatsoever, including but not limited to for purposes of advertising and promoting the Software;"
In other words, you convey ownership of any mods you create to Bethesda.
Another interesting line:
"Customized Game Materials must be distributed solely for free;"
In other words, no charging for your mods.
One more:
"Customized Game Materials cannot contain libelous, defamatory or other illegal material, material that is scandalous or invades the rights of privacy or publicity of any third party, or contain any trademarks, copyright-protected work or other property of third parties (without a valid license);"
Looks like nudity mods are now illegal - or at least you can get sued for them.