Laymans guess:
1. If you are looking at a potential long future of difficult problems it make little sense to settle for peanuts now and be faced with paying "retail" for future care.
2. If that machine has a long history of worker and customer injuries --there may be other exposures the employer may not want to address in open court? (True WC puts a damper on things--but employer may have exposure he rather not address?)
3. I agree some master the art of faking it--and it makes it harder for those who don't. (Usually its back injuries?)
4. Lets assume hand will never be normal--what about payments for adaptive retraining for some new skill area? And I don't mean a weekend miracle course designed to make you a millionaire by learning to flip houses