I don't understand what you're trying to say. Are you trying to say that the large sidewalks could've been originally built like that, back in the 1900s? If so, they definitely weren't. I know that streets, sidewalks and buildings existed back then, but from older photographs I've seen from large metropolitan cities in the Northeast, they definitely weren't built with large sidewalks like that at that time.
The OP's original question was why the sidewalks were that large, so that's all I was attempting to answer, as, I agree with them, it's very unusual to see sidewalks in the U.S. like that. Others decided to start discussing the buildings and about there possibly being lawns that existed in front of houses back then, but I wasn't getting into that because, yes, while it makes sense and is probably true, it still wasn't answering the OP's question about why the sidewalks were widened. So, I tried to find the answer, myself. I didn't say that the buildings or streets didn't exist in the 1900s, only that the article mentioned that they were planning to expand the sidewalk around 2002.
Sidewalk expansion has been only recently done more often in the U.S., due to more bicycle and pedestrian paths being built or widened, but it's not common for all towns and cities in the U.S. to do that (more often in the Northeast). It's been done more often in Europe, in countries where residents cycle to work, school, etc. because there's more of a pedestrian and cycle culture there than in the U.S. Tourists might see their cycle paths and assume they've always been built that way, originally, but that's not the case; they've gone through many iterations and been rebuilt or widened several times over the years. Residents have documented the changes throughout the years with photographs and videos.