We try to sell the client on warranty and not having to worry about things when the cameras start to fail or the system starts having issues. We also do not compromise our install quality, even if the price is a little lower - losing a few hundred in profit to do things right is worth more to us than doing things quickly and having it look bad.
If the client wants to do it themselves or thinks they can do almost the same level of work for "free", there is really no way to win. Most commercial/industrial clients we deal with do not have the manpower to do it all but residential (and doctors offices, surprisingly) seems to be where we get the most "DIY".
A properly installed system will have the associated components such as a UPS, back boxes, conduit as needed and such.
It's hard to justify the cost when the mounting accessories cost almost as much as the camera and a UPS is more expensive than the recorder. Those items are usually not installed when the cameras are $30.00 and the recorder is $150.00. IMHO
Are they reducing installation quality? I voted no, because we went with ADT and learned that expensive cameras are no assurance of a quality installation.