Well, having an indoor cat means keeping an indoor cat happy which is a larger problem (for the caretaker) but indicative of the meta supremacy in house cat behavior.
In all seriousness I would rather take the time to care
for a house cat than to deal with the possibility of
roadkill/injury, disease, pests or other accidents of
nature. If the cat is a problem for you then don't own
one?
On the other hand, I figure that yes, a cat (which I'll never have - allergies) is safe indoors, but if they're happier outdoors... well, maybe nature will happen, but should I really imprison the cat to save it? Not as far as I'm concerned. The cat can go enjoy itself.
The point being, it's not that the cat is a problem. It's that some of us think nature should remain natural, not be pressed into service keeping us company.
In all seriousness I would rather take the time to care for a house cat than to deal with the possibility of roadkill/injury, disease, pests or other accidents of nature. If the cat is a problem for you then don't own one?