Dems spend a lot of money in places like Texas, which is trending blue as the Hispanic population grows. The bigger issue (from their perspective) is that much of the deep-red states (mostly in the South) have a very well-organized Republican base. I think I mentioned a few pages back that the Republicans have been very good at organizing a few intense interest groups into a coalition that will move in lockstep; these groups are particularly well-represented in the traditionally red states. Even in states like Georgia, where there are broad swaths of the state that are predominantly black, the minority population is still deeply a minority - wiki tells me that blacks make up only 27% of Georgia, while its capital (Atlanta) is 51% black. I think that media tends to forget that all because you see one concentration of one group, doesn't mean that they are actually the largest group.
There is a possible realignment actually happening now anyway, wherein the southwest (Arizona, New Mexico, Texas) may be trending more liberal as the Hispanic populations both grow and exercise the vote. Meanwhile, the midwest and great lakes regions (which used to be full of swing states due to their large "blue collar" populations) seem to be trending more conservative outside of the bigger cities. There is a very real belief that the Democrats have abandoned them as their traditional manufacturing and agricultural industries have been hit by global markets falling grain prices. The Republicans do listen (though I'm sure liberals would tell you the conservatives are just taking advantage of the rubes, which is itself a hilarious way to look at it IMO). This ultimately may be an example of the right-wing identity politics tantra might be alluding to.
Ultimately it is difficult to allocate money to all states because money is a finite resource. Believe it or not, these parties do not have billions of dollars in reserve, so they need to target carefully for maximum effect. It is often easier to cede control of a place like Arkansas, if they think they have a better chance to take control of Pennsylvania with those same funds. Of course that's on a national, party-wide level - there are plenty of locally based candidates who will gladly take and spend all of your money regardless of which locality you look at.
Not sure what you mean by Nancy Pelosi going up against Trump? Like, in which way?
Oh and for those of you who are questioning the existence of radical leftist candidates - the tone of your question implies that you don't believe they exist, so I'm not sure what the point of trying to convince you of that would be? Like we get it, most of the western world is more liberal than the United States. What's your point?