I represent Veracity, a manufacturer (indeed a pioneer) of Ethernet over Coax adaptors and Ethernet over UTP Extenders, amongst other things. [Please note that we offer fibre-capable products too, so my comments are meant to be informative, not pushing one technology over another].
First of all, I think this is a really interesting discussion with many useful technical points raised along with various views and opinions. I'd like to make some comments from a manufacturer's perspective.
The obvious point about copper-connected links versus fibre is that copper can deliver power via POE, which is very convenient, especially for cameras which can often be (or perhaps should be!) in hard-to-reach places to which it can be difficult or expensive to install a power spur. POE solves all of that and indeed allows remote power-cycling and reboot if a camera should hang for any reason. [Note: IP cameras are extremely reliable in this regard these days, but such situations can still occur from time to time, e.g. interrupted firmware upgrades].
Whilst IT departments can, and do, raise valid objections about uncontrolled devices on their network, it is usually not a problem so long as the devices are proven, tested, properly installed and their function, reliability and lifetime properly explained to the IT people involved. The actual extenders and links are typically on point-to-point links with only the IP camera at the far end, thus not on what the IT managers would consider critical parts of the corporate network.
One valid objection which can be raised about mid-cable UTP extenders specifically is that they often end up in odd places (roof spaces, above false ceilings, in cabling trunking, screwed to a wall), sometimes with undocumented locations. It is easy to see how IT people would be wary of improperly installed and undocumented network links as any faults or failures would be very time-consuming to trace. It all comes down to quality of installation and device selection.
An alternative to mid-cable UTP extenders is to use long range point-to-point devices, so that the base and camera ends are all properly located. Such devices can deliver full 100BaseT performance (and deliver useful POE) up to 800m (2500ft) or more, providing incredible flexibility in the positioning and installation of IP cameras around a site without going to the expense of fibre and separate power cabling.
Another perspective is that very often there is coax cable already installed and where older analog cameras are being upgraded to IP cameras. The coax cable is often embedded in the building and typically expensive or disruptive to remove and/or recable with network cable. This is the reason why there is such a large market for Ethernet-over-Coax adaptors. POE can be delivered over the coax too, making retro-fit of IP cameras extremely rapid, efficient and reliable. Usually all the coax cabling comes back to one point where it is convenient to connect all the base coax Ethernet adaptors to one or more network switches. From there, the network can be linked into the corporate network, or kept separate, depending upon requirements. In our experience, IT managers have no issue with the re-use of this cabling (which usually belongs to the security department anyway) and the connection of the end result to their network - so long as they are properly consulted.
Veracity started delivering Ethernet-over-Coax adaptors about nine years ago, followed shortly after by network extenders and long distance point-to-point devices. With few exceptions, these devices are all still in place and functioning perfectly many years later. We have found that many IT managers who were initially sceptical have been won over by the simplicity, reliability and low cost of such approaches.
Our advice therefore is to discuss in more detail with any IT departments who may be against fitting network extender or adaptor devices. Often such objections can be overcome. Sometimes, however, the IT department has the final word and won't be moved. In such cases we hope that the IT department's budget is paying for the fibre links and power spurs required !