I see most of this as a pointless distraction. There already are walls and barriers along much of the border anyway, so it's obvious that the question isn't really about whether there should be a wall or not. Both parties have supported border security and claim to be against illegal immigration, at least in theory. On the other hand, both parties have also been turning a blind eye to the situation for a very long time, at least in terms of going after the employers of undocumented immigrants. I've also heard some argue the economic benefits of illegal immigration, generally using the argument that "they do the jobs Americans won't do."
This is really nothing new. This overall debate has been going on for decades, so regardless of Trump's possible motivations for pushing this, I do think it's way past time for both parties to poop or get off the pot regarding this. Both parties seem to have a split personality regarding this, and both seem to want to eat their cake and have it, too. They enjoy the benefits of having a cheap, under-the-table labor force while lacking the principles and backbone to make them totally legal (which would make them subject to labor laws, minimum wage laws, worker safety and other rights).
This also relates to a similar split personality over our relationship with our neighbor to the south. On the one hand, the powers that be have touted a "good neighbor" policy, free trade, and consider Mexico to be a close friend and ally of the United States. On the other hand, there's a lot of fear-mongering about drug smuggling (which both parties have stoked in their support of the war on drugs) and other alleged "dangers" in relation to Mexico and the rest of Latin America.
Trump may be the center of attention at the moment, but the reality is both parties are to blame for this mess.