Here in Texas, with no knife restrictions, I own an Ultratech dagger that I'll admit I purchased simply for the cool factor. It's a limited edition with full serration on one side and all blacked out blade/hardware. Very bad ass, but I never use it for anything other than as a letter opener.
Daggers, much less OTFs in general, are all but useless for any sort of real world use stations due to the extremely fragile needle fine tip and added maintenance needed. OTFs all suffer from tight tolerances and complex moving parts inside a sealed handle, so any glue, tape, etc on the blade will gunk up the works if you're not diligent about wiping the blade off after each use.
That being said, I love side opening autos, and my Ratworx MRX gets a lot of carry and use. None of the issues with debris fouling up the action, and the tanto blade is very durable. Added bonus that I can choose to open it quietly and discreetly when I prefer not to attract attention in public.
Would I buy an auto if I only owned and carried one knife the rest of my life? No, but they make for fun additions to the collection and EDC rotation if your local laws allow.