Let 17-year-olds vote? That's the argument here, not a new one. Similar, in fact, to questions about whether people should be required to vote (as in Australia). All are designed, in some fashion, to increase political participation (i.e., voting).
Would lowering the voting age have such an effect? Probably not. The question above is about municipal elections, not state or national elections, but by adding 17-year-olds to the mix, you've increased the number of eligible voters, which means the percentage that actually votes would probably go down. Math is funny that way.