Roof repair question
As part of a remodelling job our contractor removed a wood stove from our family room. The removal also included removing the chimney pipe and patching the roof. The contractor patched the roof but used tar and did not replace the shingles. He claims the difference is just cosmetic, and that replacing the shingles would mean he would have to replace a much larger area of shingles and could cause more problems than it would resolve, yada yada. Everything I have read about this seems to suggest replacing shingles is not that big a deal.
So my questions:
Is the replacement of shingles just cosmetic or will it lead to problems later?
Is it really that big a deal to replace shingles?