Analogies work so long as the two things being compared remain analogous. It was my opinion that this is not the case with banks in other MMOs versus containers in boundless. There are additional details about banks that we know won't work in Boundless (shared inventory across instances, person specific, etc.). There are additional details about containers we know don't work with banks (public vs. locked, can be placed anywhere and not just found in central locations, etc.). You're welcome to feel differently, just sharing my reasoning behind saying Boundless =/= Modern AAA MMORPGs that have had years of polishing.
When you were counting did you take into effect the increased stack size in Boundless? 99 vs 64?
Things on your person or in a guild chest are not in your house. Coins are not in your house. Skills and experience are not in your house? I'm not sure what a brain is in this context. If you mean skills, pretty sure that's going to be bound to your character, not items you place down.
As for guild beacons, we have 0 information about them so it's hard to include them in this discussion. But @Heurazio makes some excellent points. Also to be considered is what happens if the guild is multiple hundreds of players large. Doubting any one person or entity can house all of them. You could propose that the guild gets more plots with more members, but that's how Towny in minecraft works (speaking of analogies) and it's WAY easy to use to abuse smaller groups.
And if they're offline? That's what we have plinths for.
You don't have to trust anyone...it takes me months to trust people I game with that I don't know in real life, especially on Minecraft servers or in raiding environments on WoW/ESO. Careful of assuming how people play. Assuming guild beacons/plots allow for them to house all of their members, I personally plan to use my allocated space to build a portal to my own beacon outside of the guild where all my valuables are kept. Step 1 to keeping things you don't want to lose is to not give them to someone else. Which is what @Heurazio is saying.
So you don't have to craft your own beacon. But your stuff is taken anyway. And you're ok with this so long as a beacon owned by you isn't affected?