Part of the problem w/1795 is the divergence the writers took from established history by necessity. Originally, the timeline for the deaths of Josette, Naomi and Barnabas were to have taken place in the 1820's. We can only speculate why these events were pushed back to 1795 (the availability of period costumes, for instance). Nor was Jeremiah, the central ancestral figure, supposed to have died during these events - he and Josette were supposed to be Elizabeth's and Roger's great grandparents. Collinwood wasn't supposed to have been built until 1830. Jeremiah was supposed to be in the same age group as his brother Joshua, not the same age as Barnabas.
The decision to kill off Jeremiah was probably dictated by Anthony George's desire to leave the show and had perhaps the biggest impact on changing the established history. I would have preferred to see the part recast, thus salvaging an important historical plot point.
While 1795 is my favorite story line I'm not blind to its faults. The pacing is decidely off, again perhaps necessitated by Anthony George's unexpected departure. I feel it should have culminated in Josette's death (and may have been originally intended so); instead she's killed off about half way through and the whole Nathan/Millicent storyline seems like a lot of tack-on at the end rather than being interwoven with the rest of the period.
I think what makes it my favorite, aside from the time travel element, is that it represents a time when the actors were given challenging roles to play and acted the heck out of it, and it was during a time when the writing was still sharp and the dialogue still interesting and creative.
I too wondered why they simply didn't recast Jeremiah with another actor as they already did that with three characters one month before. It would have been better off that way. Looks to me like a hasty decision by DC that would become the norm in later years (ex. Carl Collins should have just been written out of 1897 by leaving town as Andre was in 1795)
1795 though, is a great, tightly plotted story that they had a beginning, middle, and end for and it was written better then 1897 was. 1840 is also close to 1795 but not as much in terms of plotting.