The threat was arguably exponentially worse during the XP era - Windows boxes with a huge default attack surface were directly connected with public facing IPs to a 32-bit IP space that could be trivially brute-forced by worms. There's a reason we haven't seen anything as bad as Blaster in the past decade: NAT.

The rate of finding exploits and what the definition of a vulnerability is really what has changed - now the definition of is much broader while at the same time, exploitability has dropped off due to mitigation in modern operating systems, compilers and CPUs. Overall, we get far more exploits, but far less of significance.