When Gmail's spam filters are working perfectly, no one talks to us anti-spam engineers. But as soon as something goes wrong, our users, our friends, and even our Google colleagues who use Gmail for their corporate mail are sure to tell us. That's just the way we like it. Spam is not something people should grow numb to and accept as a fact of life. We *want* people to complain. That's the only way things get better.
This gets a big "Umm... What?". Ideally, you should only want people to complain about things you can fix, so people see you as fixing things for them. Having people constantly complain at you puts you on the wrong side of the problem.
Second, this means that Google's spam algorithms do break (hopefully only as spammers adopt a new strategy) and that Google can't react fast enough even with the scope they enjoy.
Third, is spam still increasing? Spam volume has increased, however we really only care about spam volume / ham volume. Maybe that ratio has fallen, and a job-insecure Brad is trying to fan Spam Terror! flames.
The grim morning crept upon Brad like no other; undeterred, he gathered the strength to face the unrepentantly ugly HR troll. "Look at the recent increases in spam tickets per Gmail™ user!". declaimed Brad as he valiantly battled for his friend's lives....