In spite of having problems with FO3, I felt less fulfilled playing FO4 over playing FO3. FO4 played like a checkbox ticker. Clear out enemies at Point A while picking up magazines and bobbleheads and discover locations at Point B. I felt like I spent more time ensuring I collected everything than actually playing someone interacting with a world, ensuring that I maximize affinity with every companion so that I could get that sweet perk, ensuring that I collect every weapon and display in my framerate-breaking settlement that I'll rarely visit unless I need to modify my gun (and even then, I'd much rather skip the inconvenience of fast-travel loading and just cheat-console crafting items into the nearest weapon workbench). Having finally completed the game just now despite my best effort in over five years, I could say easily that this has been an exhausting experience I'll probably not revisit again in another 3-5 years. It just feels so unfulfilling, even with quest mods installed. I had the Brotherhood destroy the Institute and the Railroad and all I got was a pat on the back. And other than the ending, the rest of the game just feels like tourism through Boston mixed with amusement park shooting galleries. 80% of the game had you either 1) accepting quests because you want to help people, or 2) accepting quests because caps. There's rarely a middle ground like New Vegas where you side with a group of raiders and destroy a settlement. Yes, Nuka World technically had that, but god, it's such a shallow way to implement that. The raiders are no different than your default settlers. They act like your default settlers, requiring food, shelter and water, but no different than that. They don't actively go out on missions to destroy other settlements. Your reputation isn't ruined anywhere in the Commonwealth other than with Preston (and god, even the way Preston got pissy was so lazily implemented too; at least add a whole fucking quest with me and Preston fighting to the death or something).
Sigh. Fallout 4 left me feeling like I've just wasted an entire month doing nothing. It didn't make me feel fulfilled. It didn't leave me feeling like I've experienced a world where I truly had a hand in shaping people's lives, interesting unique people with their own stories. But I digress. Back to FO3.
FO3 might have shared FO4's broken roleplaying foundation, and then some, but at least it bothered to have a lot more options in how you want your character to feel like. There's a fulfillment that comes from your actions having visible and solid consequences of which you could first-hand experience (not through a series of fucking slideshow). Blowing up Megaton, enslaving Red, killing everyone in Tranquility Lane, killing everyone in Underworld, having Three-Dog being disgusted by your repulsive actions, etc, etc. These all have meaningful effects you could experience for yourself the way one would experience having to shoot a certain character in the back yourself in Mass Effect 3 because you neglected to save the genophage cure in Mass Effect 2. So yes, FO3 is a far better RPG in that sense because it at least lets the player experience the wickedness of their actions first-hand, albeit not in the kind of meaningful ways in Dragon Age: Origins, a far better RPG than both FO3 and FO4 combined (you could literally recruit the villain in DA:O if you decide your character is a pragmatic person who sees the war in terms of ruthless calculus, but you can't recruit Kellogg without a mod).
I think that's what it comes down to, really, the ability to make decisions on what kind of player experience you could have. Whereas FO4 is a one-way road with (sometimes) two lanes that merge back into the single road, FO3 is more of a two-lane road from the start. It's not much of an improvement for an RPG, but it's something.
