Just as a citizens letters, papers and home are inviolable, should our new papers our new homes be also inviolable - if I own a device, No-one should legally be allowed control over it?
But yeah, if you paid for it but can't root it, you got ripped off.
Then tech companies might start leasing out their devices: you technically don't own it, so you're not allowed to do what you want to it.
Not that the Right to Root wouldn't be nice, but the change in attitude has to come first. And we need to somehow convince the likes of Apple that their DRM is bad for business.
If the signatories to the US constitution owned slaves, I can use an iPhone while still wanting the Right to Root.