Why would Charlotte be any worse than Arlington or Cumberland, Georgia?
Well Arlington and Cumberland are both suburbs of cities that happen to be much larger than Charlotte, so there's that.
But to get to the point, Charlotte already has the NFL, NBA, and an MLS team coming so that's maxing out the sports dollar as it is. The NFL team, the one that is the most popular in this city and state among the 3 major-league teams, fails to sell out in lean years (in fact they failed to sell out the home opener last season, and they always sell that out no matter what). The NBA team has very few actual fans, most of the attendees are there for the booze and/or to see the star players on the opposing team. How the MLS will do remains to be seen, I'm sure they will be a hot commodity at first but if they take the route of the Panthers/Hornets and fall into mediocrity most years, expect empty seats. This city overall is pretty fickle and fairweather when it comes to the sports teams. Such is life as a transplant city I guess but the reaction in lean years is apathetic at best.
MLB would require a brand new stadium, likely Uptown since that's where most of the "action" is. This would mean tearing down the 6 year old BB&T Ballpark which was already a hassle to get built thanks to a lawyer who claimed the land should be used for a bigger stadium and kept suing the city, and rebuilding the infrastructure. BB&T Ballpark was not built for MLB expansion. And, Charlotte already had a big controversy building Spectrum Center in the 2000's, the original Hornets left because of it. No potential owner is going to pay for this likely billion-dollar project out of his own pocket, and frankly as a Charlotte taxpayer, my taxes are already high enough as is, and I would rather see that money be spent on improving public infrastructure (in particular the poorly lit, narrow, and pot-hole filled roads!) and getting the light rail to run a line out to the airport, than building a toy for a billionaire for a team that, lets face it, is likely going to be mediocre most years anyway. Plus, this just my own opinion but minor-league ball is a lot of fun and a more enjoyable experience than the majors.
And then there's the sheer number of home games. 82 home games is a lot, and those home games in the dead heat of July and August (especially against the non-draws) are going to be a tough sell with major league prices. With the Knights, the tickets are cheaper and the team usually offers dollar beer or dollar hot dog nights on hot weekend nights to get more people to come out. That's not happening with an MLB team. The only way an MLB team here would sell out year round is if they were the 2nd coming of the 1996-2003 era Yankees. If the 8-home game a year Panthers fail to put butts in seats in lean years which they already do (see last season as a good example), I'm not sure why the Carolina Knights or whatever would be any better. This city is way more of a Football town than a Baseball one.