Because it is convenient. Now, if I am at a restaurant or some event with company, I will use the utensils, so as not to embarrass others. Otherwise, why should I care, unless the meal falls apart in my hand?
Camping sporks are fine. Plastic ones not so much. Luckily we have few of them.
What we had instead, was the knork.
It was mainly made for eating hot dogs and potato mash on a paper tray. You were supposed to stand up while eating so you only had one hand to eat with. You were supposed to cut the damn sausage while pressing it down into the paper tray with the knife side of the fork. This never worked well. But of course it was sharp enough to cut your mouth while being used as a fork.
Since then they came to their senses and you can either get a standard plastic fork or a knife and fork.
I'd say for. The spork cannot stab stuff quite like a fork, nor can it scoop liquids like a spoon. That said, a spoon cannot stab stuff at all, a fork cannot scoop liquid at all. I think where the spork shines is in situations where you can only have 1 utensil, for whatever reason. The spork, though a master of none, is a jack of all trades.
i like to eat with my hands too, adds an extra (tactile) sensory dimension to food. I heard there are cutlery-free restaurants, precisely for that reason.
The proper way doing so before forks became widespread (15th century or so?) was with your thumb, middle- & ring-finger, not using your index finger. That way you supposedly don't end up with meat juices running down to your elbow - it works, don't ask me how (sure there's an explanation).
On the note of sporks, they sound like identity-politics overspill into the cutlery drawer (in other news, http://www.breitbart.com/london/2016/08/17/labour-run-council-to-drop-mr-and-mrs-to-avoid-causing-offence/ lol.)
Still a tad too binary if you ask me. Sporks need to proudly bring out their repressed 'knoife' side, i.e. have the sides turned into a nice sharp blade, that way you can get a jolly Joker face when eating the alphabet soup.