Oddly enough, I had the same idea just the other day, although I put it down to media overload.
No way! I have to put it down to deliberate media avoidance. What kind of Presidential candidate (ie person who's paying for as much media coverage as possible) avoids free media by not having a press conference for almost a year? Her campaign was over scripted to the point that she would not come out with positions because they might motivate opposition. It was a rehash of the, 'we have to pass it to find out what's in it,' idea. We were just supposed to trust that she has positions that we'd agree with once she got into office.
To get through to the average voter, you need to do something memorable. A well thought out, detailed immigration policy is far less memorable than "build a wall." So the average Joe, who is more worried about making his car payment this month than who is President, and is bombarded by dozens of commercials each day for hair care, a new auto, etc., not to mention the talking heads from Fox and MSNBC, will remember the guy with the simple, albeit unworkable slogan than the gal with the detailed plan he fell asleep halfway through or has to look up. Thus, "Trump will stop immigrants," and "Hillary has no plan."
Didn't hear a well thought out plan from Hillary, didn't hear her even try to articulate it. She had opportunities to speak to the country, and she choose to forego other ones. Her paid commercials most often focused on one of two things, Donald Trump is bad (or scary), or Hillary is inspirational. I get why, after President Obama won on a "Hope and Change" message she thought she didn't have to have a message either, but expecting to get an equal resonance effect to one of the most gifted public speakers we've seen in ages in silly.
Thus the arguably least-qualified candidate in living memory beats out one of the most qualified candidates because no one has the time or impetuous to find out what she really wanted to do. 
Disagree, she deliberately obfuscated and tried not to have a message, it's a not a failure on anyone else's part that she made that choice. I really think her strategy was tied to her own awareness of how unlikeable she is, she did not want to be out there with the focus on herself. A mistake? Probably, could it have worked for her if she'd be a fiery and passionate advocate on issues? It would have motivated her base, but I think her team was paralyzed by not believing she could keep it up and aware that any missteps would alienate people who'd otherwise vote for her on autopilot.
I think we're going to have to agree to disagree on her being one of the most qualified candidates, honestly, she should have been disqualified based on her record. Trump is a bad example, because he personally has so many ridiculous negatives he also should have been effectively disqualified, however, the idea that a non-politician with success in another field is not qualified to be President should be thrown out the window. Highly successful people may have gaps in their experience but they also have a great amount of experience in overcoming obstacles and in self education.