Why do movies based on video games seem to never do to well?

The movie based on the Borderlands video game series came out this weekend, and critics and audiences are crapping all over it, It always seems like movies based on video games except for Super Mario Brothers (the animated one) and Tomb Raider just don't do too hot.

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1 mo
I'll add another to the exception list, The Sonic movies
Why do movies based on video games seem to never do to well?
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