That is called 'Modder's Paradise'.

Or, as us console players like to call it, "The Half-assed End of the Map".

I think I preferred the good old cliff face or other huge, impassable obstacle blocking my way.

Beth like to put rivers and cities beyond the invisible barrier. Its more annoying that way.

At least you don't get killed by slaughterfish like you would in ESOTU.

I think they did a pretty good job with the annoying part. You literally just stop, with wide open wasteland in front of you, and you still have a little ways to go before you reach the map border (especially annoying considering how far past the map you can go on the opposite side).

I've got pretty tired of every game environment existing in a valley. I don't care for invisible walls either, but at least there is a view instead of a valley wall. Perhaps the next title should have an endless sea of armor and flesh melting lava surrounding the play area.

Don't punish me because you don't want to mod. I still need my open spaces. Not much I can do with a cliff face...

This. It's the easy space to plop down stuff if modding will allow players to open it up. However, that does mean practically one content mod for that space at any given moment.

I'm personally guessing it will be DLC area though. Maybe a Zetan staging area? A ship crashes nearby, and they're pissed about what you did to their dude. Something like that.

Head south from rivet city in FO 3 and there is an entire city on the far side of the water you can walk along the edge of but not enter. In Oblivion as you are leaving the prison there is a hole in the ceiling showing a massive room, but if you TCL there it's just a few textures only visible through the hole.

It is called background design... most of the stuff you see in non open world games falls into this category.

You guys are just too spoiled by Bethesda letting you go everywhere.