I wish people would do the math on the LCC. If you really have to get there the majors are better since their route structure is more extensive and they can reroute you lots of different ways. So if delta is 300 and spirit is 280 delta should be the obvious choice but the average pleasure traveler doesn't get their and yells at the agents about how they really have to get to their wedding that they will miss because the weather canceled one of only three flights to get their in the LCC of their choice.
It's a weird thing when a passenger buy a tickets.
To give you an example, a few years back, people would pay $40 less to fly ORD-CLE-MIA (google the distance) on a erj45 vs AA ORD-MIA, that was and is still common.
LCC's are attractive to a lot of passengers, JB, NK, VX and oh I forgot SW. They all offer a service for less than the majors -legacy-, and sometimes a lot less.
Many times the math works for the people to buy tickets on LCC's and it shows that way , since all of these LCC are successfully working their routes.
I agree with you about frequency, but most today do have a way to re-route you and non of these LCC will leave you behind with your wedding dress because of a weight limitation -carrying extra fuel for weather-, you are aware of the smaller jets that fly for the LEGACY's?, yeah the leaving you behind happens everywhere, and weather also affect the LEGACYs, when they cancel for weather everyone knows.