From this Canadians perspective the whole thing seems quite bizarre. At one time, over a century ago, the current system may have made sense, since travel and Campaigning were much more difficult. With air travel, TV, Radio, and the Internet though, it just seems to be drawn out for no particular reason.
It seems to also favour the Incumbent. The Challenger(s) need to first raise money then spend millions just to see who will challenge the Incumbent, then the Challenger needs to again return and raise more money from the same people to mount the challenge. OTOH, the drawn out process gives the Challenger the opportunity to be seen.
I think part of the problem is the Party System that has developed. It seems to me that the US Governmental System was designed for Independents and that Parties were not what the Founders had in mind. Along with comments made by some of the Founders, the Independence and Separation of the Office of President from either the House or Senate, I believe, illustrates the point. That point is that the 3 parts of the Government were designed to offset each other, to force the 3 to compromise with the various sentiments that is their speciality. The only way to accomplish good governance with this structure is for each part of Government to be focussed on their task and to bring that focus to any issue that is raised, that can only work if the 3 parts are Independent of each other.
What a Party does in such a System is to introduce a fourth level of Government, a level of Government that is beyond the reach of the People and which operates beyond the view of the People. Whereas Independents would be solely focussed on their Constituents, the Party Member is focussed on their Party and the Agenda of that Party. In the current situation with 1 Party controlling all 3 parts of the Government, the Government simply can not function as designed. There is too much coordination and too much Party pressure for the parts to offset each other.
This is quite the opposite to the British Parliamentary System which did have Parties in mind and not Independents. The British Parliamentary System also has 3 main Parts of Government:
1) The Governing Party: Party which wins the most Seats(most elected Members of Parliament)in an Election. It is also the Party whose Leader becomes Prime Minister
2) the (Her Majesty's)Loyal Opposition: The Party with the second most Seats. It gains special Priviledges as such compared to other parties that make up the Opposition
3) and the House of Lords: Largely a Patronage appointment for those who have served well, in this day and age(at least in Canada it is, although we call it the Senate). It is mostly powerless, but is charged with Oversight of decisions made by the House of Commons and can send Bills back to the House of Commons with suggestions