I can't remember the last time I used a carto... but a kept a couple of hundred pre-boge-gate boge cartos and a pretty big handful of smoketech shorties... And, I bet there's a few boxes of dual coil smoke techs somewhere in my stuff.
When I used them, it was because they were fairly consistent and not real difficult to deal with. Filling them was always sort of a hassle... They were an OK way to vape a tube mod without carrying too much extra stuff or dripping while driving etc. --> Using them on a REO was incredibly simple. But, they were somewhat wasteful (always lose at least a ml of juice when it's time to toss one)... And, when some better performing commercial attys came out (i06, cisco aero, hh.357 etc), I couldn't find any reason to continue to use them on my REOs, and I had stopped using tube mods.
I'm not entirely sure why I've never traded, sold, or just thrown away my fairly large supply of cartomizers. I guess maybe I hang on to them because I know they would serve me just fine if I ever had to take a couple of steps back down from my rebuildable bottom fed attys. I don't think there's anything wrong with using just plain old cartos... but I like the vape experience I get out of what I use now somewhat better.