Yes, it's more secure. If it's going to randomly guess at passwords, they now have additional things to try for each place in the password. If it's just letters, it's 52 guesses per position. Add numbers and it's 62 each. Add the common symbols and it's in the 80s. While systems will force that a number and symbol and mixed case are used, it doesn't force where, so a system that's trying to guess at passwords has to try all the possibilities in all the positions.
Very rarely are passwords just guessed at anymore. Most systems have a limit of how many bad attempts can be made before the account is locked, so unless they're lucky they don't get anywhere.
In many cases, passwords are obtained from systems that have been compromised in other ways. You don't need to guess at passwords when you have a whole list of the accounts and the passwords they use. In other cases it's from phishing attacks where somebody is duped into typing their ID and password. Because people often use the same password on multiple sites, then that gives them access to all sorts of different things without any guessing or additional hacking.