Boundaries are important. Whether it's in one's personal life, at work, in school or at home ... Everybody wants his privacy respected. This is not different when it comes to territories and houses. It may be for various reasons but the bottom line is that, people care about the things they own and it is natural for them to try and protect and establish some boundaries.
Fencing is a property owner's right. Such owner may be putting up fences because he wants to be protected from the unknown outside or just so he can inform everybody which part he already owns and impliedly tell them that beyond the fence, they have no right anymore. The neighbours do not have the right or do they have an opinion about how the fencing should go about. They can not dictate its color, its kind, the material used, its design and even the height. They can not do anything even if the fencing done is an eye soar.
But they are of course not totally without remedy. They can always try and appeal to the better nature of their neighbour who put up the fence. They can ask nicely to make some changes so that the fence would not be an eye soar, or they can also offer to make the changes themselves, at their own expense. If all else fails, they can just plant trees and shrubs in their own territory to block the ugly view of the fence.
About the height, though, there is still hope to make changes on to the neighbour's fence if the same is blocking a good portion of the air view or sunlight the others. In every place, there is a law that regulates the height of fences that one can put up. Normally, the height limit for fencing height is 1.8 meters. But it still depends on council regulation. The thing though is that a neighbour can not compel the owner of the fence to cut it down or reduce its height. Requesting for it is of course a totally different question. But as regards having the right to compel him to do so, the law does not grant such, regardless of how it is blocking the view of the other, as long as the maximum limit is not violated.
As regards adverse possession based on fencing, the answer would depend on the governing laws of a country or a state with regard to property. Adverse ownership is ownership based on possession with a claim of ownership. If a person fenced a place without actually having title to it and the neighbours acknowledge that he is the owner of the same, and no one is saying otherwise, can he apply for quieting of title based on his adverse possession, the delineation of which is based on the fences? The answer to this question depends on the governing law and jurisprudence in such state.