The DMCA in the most basic concept of circumventing copyright protection could be tolerable, maybe. But, the concept has been so twisted and the scope has crept, nay, launched so far beyond protecting copyright that it must be terminated with prejudice.
It's replacement has to place requirements on protection mechanisms to allow fair use, or it cannot be implemented. If a protection mechanism is found to be prohibiting fair use, then circumvention would be allowed. Any mechanism replacing one to have been found prohibiting fair use would have to be reviewed before being allowed to be implemented and would still be subject to possible circumvention allowance.
Protection mechanisms have to actually be protecting copyright. Carrier lock on cellphones does not qualify, and would not be afforded protection from circumvention under the law. Creatively designing a product to place copyrighted material in the realm of non-copyright material does not qualify. So making an ink or toner cartridge "smart" so it's protection mechanism extends to the the consumable does not qualify. Any design found to be artificially creating a revenue stream due to placement of copyright does not qualify. This is only a start, I'm sure others can contribute excellent ideas of reasonable constraints for a copyright protection mechanism law.
Copyright is important, but is has to be reasonable. Open source (which I prefer) depends on copyright to be able to enforce the source remaining open. Copyright allows creatives to earn a living, but extreme capitalism has twisted copyright to their benefit at the cost of creatives. It is this twisting that has brought us the DMCA in it's current form.
I understand the concept of a manufacturer simplifying to reduce cost and using the same platform for both the base model and top end and everything in between. I do not agree with using "locked" settings to achieve this. You leave out hardware or substitute lesser hardware to differentiate. My truck is very basic with few extra features, but is has the same wiring harness of the top model. All I have to do is purchase the trailer brake controller and plug it in to add that functionality, as it should be. I do not have to hack the settings to enable an already present trailer brake controller, and worry about a DMCA violation.
I have hacked (in the old MIT sense) the family coffee maker, some call it a Keurig, to use whatever coffee no matter how packaged, with or without a Keurig k-cup license, in any manner the machine can produce the beverage. I have sworn off any vehicle which required manufacturer permission to replace components non-essential to core functionality so the vehicle can remain functional. My main computer is over 10 years old, has had a few upgrades/replacements and still does most everything I need and/or want.