Thank you for opening this discussion. Being a validator on Celo, of course I’m in favour of restoring the original 75k cUSD rewards 
There are few more factors to consider than those you mentioned:
- Although most validators currently run their own validator group, there are few (like myself) who are a member of a validator group that is run by a different entity. My validator group, for instance, charges 25% (which is fine, no complaints) of the validator rewards.
- Having internalised Celo’s vision of “Prosperity for All”, I’m donating 10% of my rewards to the Celo for Global Health wallet (run by myself), which will be donated to an international health NGO at some point to implement a Celo-based project in Africa.
- In my opinion, what should not be neglected in the calculation, is the need for node operators to be available 24/7 so that they can respond to exceptional events like system failures in a timely manner, also during the night and holidays. This may not be a problem for large operations who employ several staff that can rotate this availability among them, but it certainly is an issue for small operations. On the other hand, workload of running blockchain nodes is not too much of a burden when a good monitoring and alerting system is in place.
To sum up, considering point 1 and 2, I’m already receiving 35% less rewards than the usual Celo validator. I can still cope with the overall reduced rewards, but it would be great if these would be raised to the original levels. When calculating reward levels not only the validator infra + operation costs and actual working hours play a role, but also the 24/7 availability of validators.