tl;dr- Net neutrality's core economic value is that it regulates a common service that everyone uses to operate in a manner that's generally palatable to all. This saves everyone tons of time-and-effort at minimal opportunity cost.
Any proposed change to net neutrality should demonstrate that it:
Has a real economic benefit, e.g. by significantly increasing the positive correlation between desired market behavior and profit maximization.
Doesn't impart a large economic penalty on consumers, e.g. by minimally complicating the economic question of "Which ISP, if any, is right for me?" for the vast majority of consumers.
Doesn't impart a large societal penalty, e.g. by minimally causing social/political/legal conflict, or, ideally, reducing such conflict. Both society and the market take huge hits whenever such battles rage.
Ideal market vs. real market
In principle, it'd be better if all market participants were free to do whatever they want, allowing rational consumers to engage in the economy as they desire. Then, arguably, some regulations could exist to prevent blatantly unethical behaviors, e.g. organized crime.
In reality, people aren't "rational consumers" because we're cognitively limited. We're not able to research-and-analyze all of our options at length, then come to an optimal decision after eons of careful consideration. Any market based on the notion that consumers have infinite time to consider all options is going to fail under the weight of reality.
Costs vs. benefits
The core economic value of net neutrality is to remove the extensive cost of considering highly complex options that could appear if ISP's were suddenly able to start doing whatever the heck they want, including throttling particular sites, users, etc., at different times, rate plans, etc.. Seriously, you'd have to get a Ph.D. in your local ISP's practices to even begin to make an optimal decision for yourself, and the market simply can't bear everyone spending that much time on a single economic decision.
The core economic cost of net neutrality is that ISP's and users can't arrive at optimal, customized plans, as they could in an ideal free market where everyone had the time to research-and-analyze all of their options.
Value of regulation = benefits - costs
The value of regulation is the reduction in decision complexity less the opportunity cost of the prohibited alternatives.
For net neutrality, we're enjoying far more simplicity in choosing ISP's and ISP's engaging with customers. Additionally, we help ensure free speech, saving us the costs of defending it when infringed.
For losses, we have cases where services like Netflix can use an out-sized portion of bandwidth, then that cost is distributed to all users.
While the losses are losses, the actual economic detriment from them appears to be pretty modest, while the economic benefit of everyone not having to police their own ISP is huge. Overall, the net economic value of net neutrality appears to be hugely positive.
Personally, I'm glad that I don't have to watch out for what my ISP might be doing; that'd be a real annoyance! Especially since I've lived in lots of areas where there was literally just one viable ISP.
Relaxing net neutrality
Conceivably, we might want to relax net neutrality in some limited, carefully considered ways.
Under the economic principle of coupling desired market behavior to profit maximization, relaxations to net neutrality should allow people to take options that they realistically have time to consider in a manner that better couples costs to benefits, increasing market freedoms.
This retreat from market neutrality makes sense in, say, cellular networks if bandwidth can be too limited. Then, we'd want carriers to better reflect real costs in their pricing plans.
The danger here is that our system currently allows anti-market practices, e.g. artificial market segmentation and exploitation of pricing power. These behaviors are anti-market. No capitalist who believes in the primacy of the free market should want to live in a world where such corrupt tactics are used because these tactics demonstrably result in a decoupling of utility vs. profit maximization. Any relaxation of net neutrality should ensure that customers don't have to watch their ISP's for such bad behavior.
The issue of censorship
Since the internet is a primary mechanism for information transit, any modification to it can be used to effect some sort of censorship, even if partial.
Some might argue that censorship could be illegal and fought in the courts. However, having to fight minor acts of censorship in court would be a gross economic burden. Our court systems are already expensive and overburdened; we don't need more of that, nor do we want to effectively require that everyone have to get involved in suing their ISP over such issues.
