In the launch version of the game, and its first patch, 1.1.30, you could enable the "Data Files" menu option via adding "bEnableFileSelection=1" to your Fallout4Prefs.ini. Allowing modders and users of mods to have easy early access to managing enabled plugins and their load order.

The "Data Files" section of the launcher has now been completely removed in the 1.2.33 beta launcher.

This wasn't addressed in the beta patch notes. Why was it removed?

One might assume because it was a developer hack they forgot to take out?

Or maybe they don't want mod added effects skewing beta bug reports. Their beta is for vanilla game unless otherwise stated I guess...

Or they might have forgotten.

Also possible they never intended to allow ESM/ESP based mods to be selectable until the CK was out. Which I frankly would not be too overly upset by since otherwise it allows Snip to reek havoc on things for 4 months (at least).

Or the breakage was not intentional and they'll fix it before the beta patch is live.

I find it hard to believe going out of their way to remove something was non-intentional.

Offtopic: While I would agree that inexperienced people using low-level editors such as the Snip programs to create malformed plugins isn't the best way to go about things. I don't believe cutting people off from this is the best way to go about it either, if you really know what you're doing creating your own plugin and creating one with the Creation Kit is really no different. Unfortunately I'm sure most of the people using this tool are stumbling around trying things until it stops crashing. I've gotten many private messages of people asking me how I made certain plugins and that they've personally tried loading it in the Skyrim Creation Kit as well as Snip and were unsuccessful. I'm more concerned about people who are intentionally editing records that create conflict in the future, there are a number of new FormLists that control certain aspects of construction. Not adding to these FormLists dynamically at script time creates an immediate conflict with any other mod doing the same thing.

If people want to mod they are going to mod. I don't believe actively trying to preventing people from doing so until the official tools are released are the best option.

Since we haven't had any confirmation it's still just speculation, though it certainly looks as though it was intentionally removed. Their motives are unknown, as mentioned it could be for the sake of having a clean install for beta testing.