> Why are most services/apps "cloud-based"?

Follow the money... $X/month, over Y months, is worth a lot more than a one time payment of $Z.

> why aren't there more tools/apps released that run locally?

There are plenty, but you have to make the choice to use them. Every app on my android phone runs locally with no "cloud" anything for any of them. But few users care enough to "just say no" to the 'cloud apps'.