"a new class of worker treated as an employee for income tax and NI purposes but has no holiday, sickness, or pension rights"
And this is where it is fundamentally wrong. The responsibility for employment is being split based on the size of company, small companies being split, large companies being ignored.
The "worker" is an employee of company "A" who sell the services of the worker to company "B". It is company "A" who is required by law to ensure all employment laws are adhered to, including holidays, working time rules and all other benefits and conditions. IR35 artificially transfers the responsibility of NI and Tax to company "B" under the assumption everything company "B" pays company "A" for the worker is salary. This is a wrong assumption.