If you want a .30 carbine, you should definitely get one! It is a neat gun & cartridge, with a noble history for the significant part it played in WWII & later. The .30 carbine works very well, within its limitations.
Unfortunately, a lot of people, including the military, have used the .30 carbine beyond its limitations (a lot), and so for that, the carbine has gotten a poor reputation.
When the M1 carbine was released for civilian sale, a lot of people got them. Nice light rifle, pretty cheap. I remember a lot of Adirondack deer hunters took the .30 carbine to the deer woods for a season or two. Then a lot of those carbines stayed in the closet or went up for sale the next season. Word got around that while the carbine worked, it wasn't really very good for deer.
The standard they were measuring the carbine by was, of course, the .30-30.
And in terms of down range performance, the carbine simply does not, and cannot match the .30-30. As a deer round!
The carbine will do a decent job of putting a hole in people even out to 200yds, at which distance it has the approximate energy of a standard (NOT +p) 9mm Luger round at the muzzle.
The .30 carbine does carry the muzzle energy of ONE .357 magnum loading at 100yds. IF the .357 load is fired from a handgun and the .30 carbine is fired from the carbine barrel.
If you fire the .357 from a carbine length barrel, it beats the .30 carbine handily at 100yds for velocity & energy.
The .30 carbine is a rifle cartridge, no question of that, but so to is the .22 Hornet a rifle cartridge.
The Carbine succeeded brilliantly in its intended role, that of a short, light, high capacity carbine for service troops, a weapon that the majority of people could easily learn to use effectively at ranges well beyond what they could do with a handgun. Powerful enough to stop enemy soldiers at common combat ranges, it became very popular with front line troops as well, and it did a pretty good job, particularly when supported by heavier arms (BAR & machineguns).
The carbine is a long way from the best possible gun for a lot of things, but it's an equally long way from being the worst for a lot of things as well.