Granted, but my question was about making them hard dependencies - as in, the planet mod won't load without them. That's as opposed to making them optional dependencies that Moshine could technically load without, just with a much more limited scope. Say, for instance, that I'm using Bob's Adjustable Inserters. That mod already provides long inserter functionality (even longer, in fact) and deliberately removes the Vanilla Long Inserter from the game as it's redundant. In this case, a Long Stack Inserter is entirely redundant, since I can set the regular Stack Inserter to reach up to 3 tiles away from its base, in any direction.
Now obviously, that's not something you can reasonably be expected to anticipate. People run all sorts of redundant mods that you can't account for. However, making the Long Stack Inserter into an optional mod is a good way to "hedge your bets", as it were. If a theoretical player already has Bob's Inserters or Quick Adjustable Inserters or something else of the sort, they can simply not install the Long Stack Inserter mod. With a hard dependency, that's not an option. If you want Moshine, you HAVE to have Long Stack Inserters. And that's just an example, by the way. For me, the same applies to Space Trains and Minimalist Rails.
Put it this way - which of those mod dependencies are crucial to the proper functioning of Moshine? Let's use Vanilla Gleba as an example. Biochamber? Absolutely essential. Most of the planet's recipes are crafted there. Agricultural Tower? Absolutely Essential. It's the sources of nearly all of Gleba's resources. Stack Inserters? Not really. They're handy, but Gleba would work just fine without them. Efficiency Modules MK3? Not really, either. They're nice to have, but they could be unlocked on any other planet and Gleba would work just fine. Similarly - are Space Trains and Long Stacking Inserters and Rails and such crucial?
I'm not saying you did anything wrong, nor that you HAVE to change it. You've already put a lot of work in your mod, so asking for this would be churlish. Rather, it's simply to discuss hard dependencies vs. optional dependencies.