While my experience is only up to junkyard, it is how it goes. Nothing I'll find in the junkyard or around it, even in Depot A is better than what is for sale in the junkyard. At best it will be of equal value but usually lower... Materials may actually differ but for equipment it is true. Still what use is there to find much higher materials which you just don't have the skill to use? By the time you have more than likely the vendors will have material at that quallity... Then again I may be talking out of my ass relative to what the vendors may have but my experience with material, usually when you find high waullity you just don't have the skills anyway, nor will have for many, many levels.
Interesting wourld informantion... Only need to do it once. Unique items. Well I'm sure the number of those are extremely limited and you'll only ever do those that will affect your class. One or two are hardly a measure of the vastness of the amount of quests and explorarion... Money, which is what compared to the loot left behind? Not to mention that we have more than enough money (again don't forget that my proposal isn't just to go back to the old system but to lower the value of items to also address this issue)... Experience. As far as I can tell and again I do know my experience is somewhat limited in comparison to the current content, you don't need to go out of the way to get XP. Even if you do you'll probably only do one or another which you know gives you a lot for as little trouble (time wasted) as possible.
I belive you that level and skill increasses are necessary, it was through the whole game till there, it shouldn't change as it goes forward. What I am saying is that you probably don't need to get off the beaten path to get enough skills and levels to go on.
Some of the stuff you do may branch, but odds are you do it the way it feels right to you and always do it that way. If you really get curious you can savescum to see different results and/or use wikia just to get to know. One playthrough is more than enough given that the players will not feel rewarded for doing it.
Lore is very important the first time around and only the first time around. Just like you play fallout 2 for the first time and get to explore all that cool story, after you beat it once, replayabillity does not comes from story but gameplay mechanics as you try different types of characters. How much replayabillity does Underrail begs? some possibly, but definitly without going into sidequests or exploring because it's just a huge waste of time. As for things like mass effect. This might be just me but I do not consider those things an RPG. There just isn't enough freedom and enough choice for it to ever quallify as an RPG. Anything that is not on a close level of things like fallout or arcanum do not quallify as true RPGs. At least not in my book... As such, all RPGs are loot driven.