I know with my setup i have it automatically email the requester so they know i have received their request and a new ticket number is assigned to them.If you have it turned off then they wont receive a reply.
i haven't seen a check box to that affect, but you do have the option like you said to email the requester once you update the ticket.
The way I work is that I mostly create tickets on behalf of my clients and most of the time, I don't want to spam them with every little issue. F.ex if I should install a lamp at a client location, I'll create a ticket called "Install Lamp". Now I can set due dates and such and being able to follow up on it.
It is also when I create an issue towards a supplier that I want this. F.ex if I ask the supplier a question, I want it to be a ticket, so that I can follow up on his response. If I just sent an email, I wouldn't have the features associated with a ticket, like being able to remember what I asked and being able to follow up.
So I kind of use Freshdesk to replace a normal email client.
It's a bit weird when people get email from me, that it comes as a reply, cause that's the only way I can send a question, it seems.