not all renovations are big, so how would it be judged when they need to be forced to remain in their property, Answer, you can't, it's impossible,
the key thing is that there are planning laws in place in the UK which ensure any renovation complies with legislation, this includes maximum % the property owner is able to increase their house size footprint, checks to ensure natural daylight is not denied the affected neighbours, to some degree privacy considerations which invariably involves obscured glass, windows angles that mitigate against loss of privacy.
the time to contest an extension and express concerns is when the planning application is first advertised, giving affected households the opportunity to object. Objections should be on the basis of light loss, not because it will reduce property value of neighbours nor that a view is lost, Views are not protected in law, nobody has the right to a view, people do have a right to natural daylight and privacy. Once the application has been approved, it's set in stone,
why shouldn't people want to increase their house size, provided it complies with legislation.
that doesn't mean I can't express empathy to the OP for their situation, but it really isnt as simple as dont extend.