Yes, I've been thinking about something like this too. Only I was trying to add our brains, throughout evolutionary development having been accustomed to three-dimensional thinking and perception only.
If we were to think in those categories, then yes, it seems that our Universe is indeed boundaryless. However, as we try to move higher in our perception, ability to visualize, we do not know what being in four dimensions would be like, feel like, if you want, and such.
It's like, we can visualize from a two-dimensional drawing, what something would look like in three-d, or, Windows NT being able to work with Windows 95 files, but Windows 95 wouldn't be able to work with Windows NT. Same here, we simply cannot/don't know what would this be/feel/imagine like to think in four-d.
Well, it so happened that up 'till "4 minutes ago", in terms of the timescale of evolution and life on Earth, we had only had to deal with stone throwing, arrow shooting, need to get in three dimensions, (in space), from point A to point B, after a battle as quick as we could, with the purpose of loot and marauding, -before- our neighbours get there first; from day one we had realized ourselves consciously, as individuals.
...
We are simply not there yet. When we are ready, (those that are left), it'll be unblocked, and many things will become much clearer than they are now.