There is no technical reason for 2D anymore; the look (if wanted) is easier to achieve in 3D, like Pillars/Torment, and WL2 have. The original Fallout would have used 3D polygons, but they could not get the performance on the current consumer hardware of the day.
*Note: Pillar's of Eternity is a 3D game.
I've said that several times; perhaps even this year.
Fallout was begun as a turn based combat engine to simulate GURPS on the PC. This was before the concept for the lore IIRC; Originally they had even the idea of a time traveling boyfriend who killed the first homonid while trying to rescue his girlfriend from dinosaurs. (Not like that would have been approved all the way to release.
) They were GURPS players; they got the GURPS license; they spent about three years on a turn based http://i271.photobucket.com/albums/jj125/Gizmojunk/Fallout_GURPS_zpspmpkf1qt.jpg, that would ultimately lose the license and need to be changed in two weeks or get canceled.
**Further down that tangent is discussing Fallout for Fallout sake, instead of FO4 speculation. Suffice to say that it was their game even with the license change, and was the best GURPS implementation for PC and Mac. All evidence of the developer's related works (and statements) before business arrangements with Zenimax, show them sticking to format with Fallout speculation and potential related projects. My SIG quotes Feargus Urquart's own assurance about any future Fallout sequel they would plan.
Now these are practical people who do not hold the reigns to it anymore; but I would bet that had they obtained the rights the rights, we'd have a Fallout 3 from them that fit the ideal to a T.
Would I prefer FO4 as TB (speculating)... If it was well designed, of course; that's how it's supposed to be. Would I want the same TB gameplay for Witcher or TES, of course not. Different series, different styles, different agendas for each. That's the problem with FO3/NV/FO4, it follows the TES agenda instead of the Fallout agenda. Wanting tactical PC reliant TB combat in FO4 is not asking for a Fallout 2 clone, it's [wishing] for a modern DX11/12 title that fully exploits the modern desktop for a tactical TPP Iso3D cRPG in the style of the series namesake; and the game mechanics to support such a system. Why on Earth would a fan of the series expect or want an FPS of it? They could have done an FPS/RPG of it in 1997, they didn't, that was not the concept for the game.
PNP simulation was; or just enough of it ~for GURPS players.
**Obviously, no one is suggesting that future Fallouts be GURPS games, but one would hope that they always keep the same priorities as intended by the series architects.
(In the same way that Strawberry Jam should always taste like Strawberries.)