Every contract entails waiving your rights and removing future options. And tons of contracts include, as consideration, the agreement not to do something. Leases, for example. If you lease an apartment, you usually have an implied legal right to sublet; correspondingly, most landlords have a clause in the lease requiring you to waive that right, right next to the clauses requiring you not to get a pit bull or smoke cigarettes indoors or have somebody else living with you unbeknownst to the landlord.
Another example is exclusivity agreements: a shopping mall might sign a contract with Panera giving that Panera an exclusive right to sell sandwiches at that mall, which means the mall is agreeing not to lease a different retail space to Subway or Quiznos. What if they lease it to Qdoba and Panera thinks a burrito is a sandwich? That was a real lawsuit, which Panera lost, not on the grounds that it's impossible to incur a negative obligation by contract, but on the grounds that a burrito is not a sandwich: https://loweringthebar.net/2006/11/judge_rules_bur.html
There are legal rights that are protected to the extent that you cannot waive them and that any contract that entails such a waiver is an illegal and unenforceable contract. It's just that these rights tend to be explicitly stated as such in law, and the right to go to a court of law is not currently one of them. Maybe it should be, but that's a policy argument, not a fundamental argument of legal and moral principle the way you're making it out to be.