BFG and Jack the Giant Slayer used too much CGI and flopped.

Both of those films could have been done with humans playing the giants and used trick photography with a little bit of CGI here and there to fill in the gaps that couldn't be done with practical effects. But by making the giants CGI characters the budgets for both films was far too high, and that's why they both flopped financially.

Plus, it just doesn't look as good. Film makers are so quick to use CGI these days as if they want to show off what they can do with the technology. Instead, the technology should only be used when you can't film something using practical effects. In the end, over relying on CGI makes these types of films look cartoonish, and it can take the viewers attention away from the story.