Some questions from a literal perspective only have a no answer. I've answered some of these by explaining how one can create a compromise solution that brings them closer to what the OP wants. These answers are rarely accepted -- should I bother in those cases?
Even if it isn't the exact solution, it is a solution.
Users come here for help - most of them don't care if it isn't done a particular way, they just want it to work.
Because you might just be helping someone who comes along later with a similar question/problem, and then they see that and say "Hey! That might work!" and then they try it and it works!
I honestly cannot think of any good, solid applicable reasons not to try and answer a question (there are always edge cases, admittedly mainly when the person is being stubborn and doesn't want a solution, things like that).
You made good points so I'll continue offering alternatives. There have been times that my alternatives for otherwise no answers have been voted down with comments like "you didn't answer the question." Some question beg a particular answer even though there are alternative solutions.– fragosMar 27, 2012 at 20:59
1@fragos Usually I make it clear first thing in my answer that it won't answer their question but at least get someone going in the right direction. Mar 27, 2012 at 21:52