In fact, it takes experience and skill to read the handwriting of our more recent ancestors. Most people can't read 19th-century manuscripts written with quill pens or even steel-nibbed pens unless the originator if the document was a clerk trained to write a Palmer or Chancery hand; the conventions (such as punctuation and common abbreviations) have changed too much. And that's assuming that the paper and ink have not deteriorated beyond legibility.

I used to work at the National Archives of Canada, and I can read just about anything written by hand in English since about 1700. Eighteenth-century handwriting is generally easier to read, as literacy was less common and even infrequent penmen (and pen-women) were typically fairly well-educated. They also used paper and ink of higher quality than was typically available 100 years later.

The least-legible documents I have ever seen were "cross-written" letters composed during the North West Rebellion of 1885. The writer, Colonel William Otter of Toronto, was short of paper so, when he got to the bottom of the page, he turned it 90 degrees and kept going. Col Otter wrote a fine clerkly hand -- he worked for more than 20 years in the head office of the Canada Land Company -- but cross-writing made his letters to his wife a complete secret to everyone but her!