a short multiple choice where you can select key policies that matter to you which then votes based on your choices, it would certainly be a lot more impartial and anyone who wants to actually vote tactically for a specific party could play the system anyway by doing their research before hand; at least it would still be an educated vote.
I'd file that under "nice idea in theory but unworkable in practice". Who decides what a key policy is? If it's the parties, they could hide away a deeply unpopular policy by simply considering it as not a key policy. Of course, they can try to hide them away at present but all the press have to do is say "x party is proposing this" and suddenly lots of people know about it, and if its a dealbreaker for them then they can not vote for said party because of it. Whereas under this system they would have to say it as "the party who is proposing x, y and z are also proposing to do this"...
If it's anyone else, there's huge potential for bias in determining the topics.
And either way it would have to be set a fair way in advance, so issues that develop during the campaign could not be taken into consideration.
And what if a voter cares deeply about a topic that all the parties have policies on but which aren't considered key policies? I'd say only about a third of my personal key priorities are ever asked in that big "who should I vote for" questionnaire that someone (I can't be bothered to remind myself who) creates each election, even when expanding it out so that you're answering literally hundreds of questions.
Plus what you would actually get is people voting based on their gut feelings about the policies presented, as decided in the 10 seconds they spend in the polling booth. Which is strongly affected by how they are worded, how they are feeling that day, etc. In other words, a very long way away from the informed opinion that you are trying to encourage.
If anything I'd say the present system is better, although I'll happily acknowledge that is flawed in exactly the way you identified.
At least our system is better than the Australian one, that forces people to vote, in that in this country the people who really don't know and don't care about politics tend to not bother to show up.