My question is why ICANN enables this market since the domains ultimate goal is not achieved.
No, it is not. What I stated is how the domain name system has operated since it started. An entity rents one or more domains. They can use them however they wish provided they are paying for it and not breaking any laws. If the domain is violating a trademark there is a process for that. Otherwise people will game any system put in place. If one feels this current system is unfair they would have to get a movement started to change ICANN policies in a way they can not be gamed and would not result in yet more artificial business models including the shady ones and infinite spawning of legal battles gamed by lawfair and so on. Hind-sight is 20/20 and I am sure the people at ICANN would fundamentally agree the artificial businesses that popped up as a result of the design is sub-optimal but they would also probably shrug their shoulders. I think you are talking about changes that this late in the game would be very challenging to navigate especially given businesses park dozens or hundreds of domains and if anything threatened this they would start flinging lawsuitsin addition to lobbying to stall any attempt to change anything. It could be a naive view to think it is only the shady re-sellers that would be impacted by changing this.
Business models pop up all the time as unintended or intended consequences of a system or busines design. Anti-spam and anti-malware could have been avoided all together but instead became a multi-billion dollar industry. Half of the medical care fields could have been avoided by people eating right and not engaging in risky behavior but they don't so there are business models built around that too. I could go on all day and night about artificially created business models. That used to bug me too but I came to the realization that I can not change that without dedicating my entire life to making changes but I would rather spend my life doing things I enjoy and just navigate the existing systems to the best of my ability.
If you have a proposal on how to address your concerns then I suggest writing it up, propose it on assorted sites get feedback to refine it and then submit it to ICANN. If you take the time to do a well thought out proposal I am certain people here could review it and try to poke holes in it. If you have a blog that may be a good place to do your write-up and link to it from HN.