To be fair...
If you buy a mobile phone, or any other kind of product, you agree to the conditions /contract that it came with.
If you buy software, you could easily duplicate and distribute copies (free or for a fee), but the agreement forbids that.
If you buy a mobile on a plan then you have agreed to take on the plan as part of the bargain.
This is no different to any other transaction that you might choose to enter into.
Don't like the conditions and limitations? Then don't buy the product! Just because electronics, software and internet are invovled changes nothing.
Perhaps the EFF will help me buy a house for 20% down but make no repayments because I don't like "the plan".