It's bad for people who just don't care about going over and think they should be able to access overdraft when ever they want. It's good for the single mom who rarely makes enough to cover everything and won't get charged even more money for having no choice but to go into overdraft no matter how well she balances the check book because a $10,000 a year job is never going to be enough where she's living.
Or, the person who has no choice but to count on money that may or may not appear (child support falls into this in a lot of cases). My sister's been hit with $45.00 fees, because she deposited a cheque that turned out to be NSF, and then she wrote, in a turn, another cheque that bounced. It happened to me once, and I got hit on both sides, because at that time, the bank was charging for bouncing cheques, and for depositing cheques that are NSF. I deposited a Christmas cheque for $50.00, and it bounced, and thena cheque that I wrote bounced, and I ended up paying $50.00 out of pocket.
The deterrent thing is a load of crap. For people who are living right down to the last dollar in their accounts every month, charging them $45.00 (current fee at my bank) for bouncing a $10.00 cheque is just going to make it harder to stay on top of things, and more likely to bounce another one in the following weeks.
As for who uses check books? A lot of post secondary students around here use them just because it's easier to cash your student loan with a void check than to have to make to the bank sometime between 9am and 4pm.
I still have a cheque book. I don't use it for much - mostly school things (field trips, gymnastics/Ultimate fees, etc.) for ds1. But, I probably average out about a cheque or so a month, over the whole year. Most people I know still use cheques for some things, especially if they have kids in school, because the schools all take cheques. I pay my rent on debit here, but I paid it by cheque everywhere else I've lived, and there are tenants here who still pay by cheque, not debit.