Even if Fallout presented itself as a non-Fallout and a non-RPG focused game it wouldn't matter to me. I played Fallout 4 on its own merits and I enjoyed it for quite a long time but uh... Let's put it like this, a film should go out on a high note, it should leave you feeling like "man, that was a good fucking film!". It should not leave you feeling like you've had to slog through the last 30 minutes just so you could finish the damn thing up. And that's pretty much any Bethesda game. It starts out neat if you just play it on its own merits but the repetition and bad design will pile up on you and by the end you'll feel like "thank god it's finally over". So even on its own merits I don't think Fallout 4 is particularly good. You shouldn't feel sick of the game by the end of playing it.
As a game on its own merits it is typically repetitious for a Bethesda game. If it had more enemy types and weapon types, more varieties of traps, more environmental story-telling, revamped the whole damage and health system for both players and enemies in favour of something more survival oriented. Maybe then it could have been better. But because of the poor variety in weapons it means that eventually you stop finding things worth a damn. Because of the limited amount of enemy types it means that you'll get the feeling of "I've done this before..." over and over again. Because of the low variety in traps it means you'll easily spot them eventually and then that risk is removed. Because of the shitty balance it means that facing elite enemies just get tedious as you pump 70 rounds in a super mutants face.
And the story is still shit. Even on its own merits it is just poorly done.
Borderlands on its own merits I found to be a lot of fun. Maybe it's because the first one I played co-op with a friend on a console and the second one had a better story and more interesting characters. Whatever it is, Borderlands 1/2 I left feeling like it was an awesome game and I was sad it was over. Fallout 4 I left feeling like I was glad to be done with that piece of shit.
It's like, if you have sex with someone and it's real good but the last 5 minutes is him tweaking your nipples so hard that you're sobbing from the pain then it ain't good sex. Doesn't matter if he made you cum twice in the first 25 minutes, the last 5 minutes is what you'll remember the most. It's easier to gloss over the good stuff than it is to gloss over the bad stuff. The bad shit sticks with you.
And Bethesda's history of bad shit is a decade long for me.