Man, they definitely show a blatant misunderstanding of what Fallout 1/2 were, and in-turn what made them so appealing. Fallout 1/2 are undeniably "post-apocalyptic science-fiction RPG's," while Fallout 3/4 are only undeniably "post-apocalyptic." Many things in Fallout 3/4 are so improbable it would be fair to lable the game as a "fantasy" (radiation turning people into ghouls, the world not being in any decent shape after 200 years, etc). The fact that they had the audacity to pass Fallout 3 off as a direct continuation of the Fallout series is almost insulting toward the classics.

They do still take place in the same setting and carry over a core group of elements from game to game, but it's an insanely superficial implementation. Sure, the Mr. Handy name appears in Fallout 3 as it did in Fallout 2, but that's really as deep as it gets (this is just an example, I'm not implying Mr. Handy was ever deep). It truly is "as wide as an ocean, deep as a puddle," which is how Bethesda games are commonly described across the internet.

It's a bit ridiculous to expect them to strictly adhere to the design philosophies that go into a isometric turnbased RPG when their games are 3D open world RPGs.

New Vegas proved that it isn't a bit ridiculous to expect them to strictly adhere to the design philosophies that go into a isometric turnbased RPG when their games are 3D open world RPGs. I don't even know what you mean by this.