and whats in my imagination is always going to be way better than whats on the screen.
This. This sums up my problem with many sandbox games. Perhaps one part of it is due to my lack of imagination, but I feel like it has more to do with my desire to see something that's real on my screen, not something that requires my imagination.
Take The Sims games for example. One of the three appeals to those games (alongside designing buildings and building a legacy of families) is that you get to "create your own stories" in a fanfiction sort of style, using the empty templates of these "Sims" as a platform to tell your stories. Unfortunately, the template of the Sims is very limited, so a lot of it comes down to you imagining any fantastical elements that the games are unable to produce on-screen.
I feel like I'm someone who's attracted by visuals. I like to see amazing things happening rather than think about them. To see and hear something that's real, there's a distinctly different feeling from when you see a mere illusion. Whenever I see something that's left up to my imagination, whether it's an ambiguous film ending or a text-based game like Planescape: Torment, there's often an empty and fleeting feeling that, even when explained, leaves me with a big "So what?"
Now, of course, much of society frowns upon such an attitude, calling it lazy and uninitiated. But it is what it is; my own personal desire to see the actual thing. A doubting Thomas I am, perhaps.
But I went offtrack a little bit. Going back to the combat, while I could appreciate the appeal of a slow turn-based system that lets you plan out things, for me, it merely raises my anxiety as I'm unable to dispose of the immediate threat that's lowering my health. For someone with my anxiety condition, I don't need stress like this in my games. I like to enjoy my games, not stress over them.
Furthermore, if I want to sit and plan out things, I would just go play D&D or even chess. Why would I want to play a roleplaying game where I should feel like I'm in another universe? To sit there and plan how I'm going to dispose of the 8 raiders slowly tip-toeing towards me? Boring. If the Fallout universe was real - and since we are talking roleplaying, let's assume it is for the sake of argument - then you know what my plan is? Attack. Just shoot them in the head. That's my plan.
You know what's a better analogy for your point about planning things out? Planning how you are going to build up your SPECIALS and how you're going to collect all the skill books. Or planning how you are going to roleplay your character properly so that you perform all the quests in the most evil or good way in accordance to your character's karma (so you know, you don't accidentally become a saint or a bastard by doing a quest incorrectly). THAT's interesting planning. Uninteresting planning for me is planning how I'm going to dispose of enemies. Shoot them, grind them, burn them, stick them with a poker; any of those would work in NV.
And let's go a step further and say that scheming how to dispose of your enemies can be interesting. Yes, it can, but only if it means you get to use a charisma check, or a speech check, or heck, even better, picking the correct dialogue options or even interacting with the correct NPC. THAT is interesting planning. I hope the nuanced difference here doesn't escape you.
The problem with the so-called "planning" in the turn-based combat is that the only planning you need to do is before the actual combat happens. You need to pick a good enough weapon which you need to plan beforehand on how to acquire it. When the actual combat happens in the older Fallout games, all you need to do is sit and click, wait for NPCs to slow-crawl towards you and click again, 'till you eventually maybe hit one or two hits on them. THAT's the extent of the planning you're referring to.