Maybe that was the only viable option back then. Today, more people are willing to pay for services and not be bothered by mostly irrelevant and annoying ads! Yet, Google isn't changing as we're the product!
I was an early adopter of Contributor, which got shot down in its original form! This speaks loudly about nowadays Google!
It is just how they make money. What they DO is make the best search engine, host every video and livestream anyone on earth wants to upload, run the best email service on earth, run the best cloud office suite etc etc.