Is it common to biopsy hypoechoic liver lesions?

Yes: From the way it looks on ct scan it can be concerning for cancer therefore a biopy is need to determine if cancer is present.

Liver lesions: Typically, ultrasound can distinguish between cysts (fluid) and solid masses. Depending on the appearance of the mass on ultrasound, it may be appropriate to biopsy based on that exam alone. Some masses aren't well enough characterized with ultrasound and require contrast-enhanced MRI (or ct sometimes) to ensure that biopsy is appropriate.