The rules aren't biased towards spinners as much as you think, yes they're difficult to defend against but it can be done. Take the World Championships this year for example, 6 of the 8 robots i fought in my qualifiers were spinners and i went into every match knowing Hatchet might not come out in one piece again, having said that when i did win a fight down to my robot overcoming the odds it was a fantastic feeling, going into a match knowing you can disable a spinner so easily takes away the competitiveness in my book.

Entanglement IMO is a cheap way to win, not to mention being dangerous for the person who has to try and remove the link of a robot covered in a net.

Also, think of it this way, you're worried about your robot/components being damaged by a spinner, think of the damage that a net could do to the set up of a spinner, it could kill the motor, burn out their speedo or do countless other things that could render it useless and cost the builder a huge amount of money.