Exactly.
I'm not going to lie, a lot of 16 year olds are pains. Not quite as big pains as 12 year olds, but pains nonetheless.
But saying they should be restricted because they are reckless shows a fundamental misunderstanding on how democracy works. Voting isn't limited to only the 25-60 age group, despite them technically being the best suited to a wide range of experiences. Voting isn't limited to only those who are in jobs, or are home-owners, or are successful.
In a democracy, you want a large range of opinions. You want a large range of experiences, you want the ill and the healthy, from the young to the old, from the rich to the poor, men and women, Black and White and Asian.
And there is already a heavy bias towards the elderly: They are more likely to vote, they live a long time (we have an ageing population) and we already deny the 0-16 year olds the vote. The average age of the UK Population is 39.9 (according to google). The average age of someone who CAN vote is 47.2 (according to my calculations)... and that includes 16 and 17 year olds can vote, and discludes the relative likelihood of the different ages voting.
If the average age of a UK voter is over 50.. It's a good thing and a bad thing. But there are definitely problems because of this.