As mentioned before, part of the problem is the feeling/perception that the “dynastic” candidate did not sufficiently “earn” their shot at power by rising through the ranks up from footsoldier.
This is of course somewhat fallacious in the sense that elective political power is not a career service track where every single step has to be gone through requiring a combination of time in service, time in grade, and passing scores in required courses and tests. Most of the people in the top tiers of power, even if relatively self-made like Bill Clinton, got there by building up social and professional relations that one day put them in the right place at the right time, leapfrogging some long-serving veterans along the way. The key thing, of course, is that they are perceived as having *worked *to get to that position of advantage.
Why is it people did not talk about a “Romney dynasty” … because Mitt sought his political career in a state different than his father, and got a whole lot closer to the presidency than his father did? But he definitely was born in scoring position, as the sports metaphor goes.
But, are we going to say, it is good if you went to the right schools and built a network… but not if you were a legacy student? It is good if you try to be a politician like dad… but only if you seek a different office?
To be fair, in practice, you look at the offices downballot and you will see Americans are NOT particularly reticent to support “political dynasties” per se. Descendants, cousins, in-laws keep winding up in congressional delegations and in statehouses and city halls across the nation, decade after decade. Sarbanes or Cardin in Maryland; Daleys in Cook County; Kennedy/Shriver and variations thereof across a whole swath of states, as are Rockefellers; Landrieus in Louisiana; Udalls across the west; Tafts in Ohio; etc.
Somehow, it’s having had someone in the family hit the Presidency, in particular, that makes people stand up and notice. Maybe because until the Kennedys it was rare to have the “dynasty” seek to actively stay in contention for that office contemporaneously. The two Adamses had a 25 year gap. Ben Harrison was the grandson of W.H. Harrison the Very Brief and was elected 48 years later. The Roosevelts were cousins a couple of degrees apart and again separated by over 20 years. However then came the Kennedys and right away it’s make every brother a Senator wherever there’s a seat available, and all seemingly HAD to run or try to run for President – Jack in 60, Bobby in 68, then Ted in 80 even with heavy baggage on his back. Then for the new century come the Bushes and Clintons, in quick succession just leaving 8 year gaps between runs (plus there has been a Bush or a Clinton either in the primaries or the general election in every race since 1980 except for 2012). This gets noticed.
Other factors creating greater discomfort include the rise of the “imperial presidency” where there is such an extreme concentration of power. There is also the creation of the media-celebrity environment around the Kennedys, where even a layabout second cousin getting arrested is “news” and every single direct descendant somehow feels *expected *to at least try to do something politically important. And the voters who support the aforementioned state- and local-level political machines may be perfectly at peace with how they are taken care of each in their turf, but worry about the RNC/DNC becoming “privatized” and the way up for their hometown boy or gal getting choked off.