So you see, ability to move and look freely is natural and pretty much unquestionable refinement of step based movement and view.
Nope. It depends what you're trying to do. If your goals for the 3d movement section of the game are modest, step based movement is a big advantage, because the player can explore quickly, using a keyboard, rather than having to check every crack, constantly look around with the mouse and try to squeeze past every rock in order to explore a fully 3D environment. Step based reduces the need for obsessive compulsive behavior, so that the 3d movement section of the game can be simple, quick but functional.
The Gold Box games would get a lot worse if they were made full 3d instead of step based. It'd be better to focus on improving the combat if you wanted to improve those games.
I believe I have already adressed this point:
A case could be made for retaining step based in a TB because it would allow much shorter travel times (a flimsy justification considering all the drawbacks, but a justification nevertheless), but in RT you need to limit the speed anyway, or you are designing a broken game
If you move at limited speed, so you can't just punch in the right combination of arrow keys quickly to backtrack, you might as well look around.
If there is no speed limit - well, you've just made a game where not just combat but even movement speed depends heavily on player's skill.
Good job.
OCD behaviour depends on both area and game design - if items aren't just lying about in realistic manner disguised among clutter (or need to be actually spotted by party to be pickable, thus announcing their presence in the interface), then freelook and smooth movement won't make your game more prone to OCD behaviour. If items are disguised and cleverly hidden - well, that's an intentional part of the game.
Case in point Wizardry 8 - the only OCD exploratory behaviour possible in this game is traversing all the corridors and combing wide open exteriors - this wouldn't change one bit if both corridors and exteriors would be made of tiles.
In fact I'd argue that freelook in itself might reduce tediousness of OCD behaviour if not OCD behaviour itself, because we are used to moving and looking around freely and can be expected to have all sorts of adaptations allowing us to scan area around as in smart and efficient manner. It's quite likely that at least some of those adaptations get shafted if we switch to stepwise movement, and multiplies of 90 degrees rotation, and we need much more effort to scan area.
Not to mention the limitations of such display mode - to ascertain whether you see a relevant object in the distance one might need to do only a minute shift of perspective - in a stepwise blobber, one will probably have to walk all the way towards it.
As for Goldbox games - they switch to separate combat screen, no?
Not exactly a case study of how stepwise movement benefits an RT blobber.