Arguably, this prevents political extremism, causing all of the major parties to the centre. Pushing more voters to vote prevents political influence by lobby groups.This is how you get even more ignorant votes. People will just do it because they have to, and a lot of people will probably pick one at random (not caring about politics).
While this would prevent lobby influence, if we have (hypothetically) a large population of uneducated people with the economic understanding of a twelve-year-old, then we basically have a group of twelve-year-olds voting. This would probably only be a problem in highly impoverished areas but a problem, none the less. It could easily be mitigated by policies, but that would clash with the whole "everyone votes" idea.
I think I might have to agree with you slightly. However, on the other hand you have a large group of informed youth that very rarely vote. In Australia only 40% of (relatively informed) youth voted, despite it being compulsory. In some cases, you actually need to give a people a kick in the backside, people that are actually informed but might be sitting in the political centre, or just unhappy with all major parties, to get them to vote.