See
sections 3 and 4, pages 11 and 24. This is from the UK telecom regulator, June 2010.
Well, from section 3.4, "network operators and ISPs are also considering whether traffic management techniques could play a role as a complement or substitute to network investment." I see no reason why I should be charged MORE money to permit network advisors to spend less. Business costs what it costs; if they want to provide better service, they can (and do) charge me for that in my contract. (I just upgraded from dialup to fiber, for example.) i don't consider this a decent argument.
Section 3.8 points out that "New opportunities are not enough to offset the decline in traditional fixed and mobile telephony revenues." Not relevant; business models can and should change. if you can't change to meet the new demands of the market, close up shop. Again, this isn't a valid argument.
Section 3.10 points out that wireless networks are overloaded. In the United States, this is being addressed by making more of the spectrum available and by (gasp) building more towers and making cells smaller --- in other words, by infrastructural investments; the companies that are investing in better infrastructure (e.g. Sprint and Verizon with their new 4G networks) are gaining market share. This is how competition is _supposed_ to work.
Section 4.12 states that "Consumers do not all have the same tastes and preferences. Some may be willing to pay to minimise the risk of receiving a low quality service, for instance keen internet gamers. If traffic management was not possible at all, ISPs could not meet the demand of these quality-sensitive consumers." This is, not to put too fine a point on it, untrue. My own personal experience shows otherwise -- as I said, I just upgraded from dialup to fiber. I can buy as big a data pipe as I can pay for; if one ISP can't do it for me, I can simply find another who will.
Even in the wireless world, this is possible; if Verizon chooses to buy another block of the spectrum and reserve it for "premium" cell customers who are willing to pay $1000/mo for cell phone service, they will be able to offer much better service because they'll have fewer customers. This, of course, is hardly new -- radios have been buying multiple licenses for different groups of customers for decades.
I'm not going to continue dissecting this document paragraph by paragraph; let me just say that my cursory reading of it still leaves me with no "decent arguments" against Net Neutrality. If your ISP doesn't have enough bandwidth for your purpose, change ISPs to one that invests properly in infrastructure.