You are jumping to the consequences of the Constitution, the Bill of Rights in particular, protecting individual rights.
Because the Constitution, the Bill of Rights in particular, protects individual rights, minority rights are protected.
> constitutional provisions aren't necessary when the lawmakers are on your side.
Except when the lawmakers are in the minority (and you being in the majority), the majority still needs protections. Since its the individuals, not minorities that are protected, the rights of the [individuals in the] majority are also protected.
The historical reality is that the rights enumerated in the amendments were designed specifically to protect minorities.
Yes, "individual rights are minority rights" implies "minotiries get rights". But if the primary purpose was individual rather than minority rights, then why in god's name aren't other more obvious individual rights (e.g., right not to be raped) enumerated as constitutional amendments? The answer is because the legislature can and will do that anyways.
If you agree with a supermajority of Congress and the President on issue X, your first amendment rights to say you support issue X aren't really super important. Of course you should still have them, but they are easily protected by way of democratic processes -- constitutional provisions aren't necessary when the lawmakers are on your side.