I think we're in agreement on the general view from R's on taxes and abortion.
I also think that a big driver of the rise of Trump was the failure of W. He had been very popular, but following Katrina, the dragging on of the GWOT, particularly all that was happening in Iraq 2005-2008, then the historic economic meltdown, it's easy to see why W went out of favor, even among his supporters. But in so doing, he may have wrecked it for "establishment" Republicans. I also have a theory--that I don't expect my Republican friends here to agree with--that one of McCain's biggest mistakes was nominating Palin for VP. While she was--IMO--wholly unqualified, that wasn't the real damage. The real damage (this is the part that I expect lots of push back on) is that Republicans caught a glimpse of just how much her populism could light a fire in the political base. After that, why run establishment when you could run on that fuel? A significant problem with my theory is that Romney was the next nominee, who certainly felt very establishment. (In my view, Romney was a Republican version of Clinton--as far as his politics, not her personal life--happy to say what he needed to say to get elected; likely captive of whatever special interests backed him.) But my view is that Palin's populism lit the fire that grew into Trump--particularly after another failed establishment candidate. Even more so when (I think) Romney losing surprised the Republican establishment (because they weren't yet as data focused as campaigns today are).
SFIrish was given the adage about politics: its like waiting for public transit. The bus doesn't come to you, you go to the bus. You have to be ready when the bus comes, but if the bus is full, or you miss your stop, you're out of luck. I think that happened to Romney. At a lot of other moments, Romney probably could have won, just not 2012. Curiously, I don't think that about McCain. Conversely, every other President elected since I've been voting (so everyone after GHWB) relied on a decent amount of luck to get where they were going. I guess they all had a certain amount of luck, but at least GHWB, Reagan, Nixon, and LBJ had long careers at significant levels of politics before they were President. Carter won the anti-Nixon lottery. Biden is probably the closest to fitting that bill. I think he would have been a strong candidate in 2016, but--again--the party wanted Hillary because, it was once again her turn, and Biden had just lost his son, which is a hard thing to just ignore while running for president. In 2020 he won the "most normal person to face Trump" award. But, damn, he was old.