As we've seen the last several years there is not much you can do sometimes when it comes to intensity. Now model intensity guidance had been very aggressive in this becoming a category 4 hurricane but as we got closure there actually became a bit more in the way of spread regarding this and for good measures.
1) There was still the potential for a farther north track. The idea was this was it would encounter more shear and dry air which would disrupt the structure and in this scenario we saw the potential for a stall in which upwelling could eventually disrupt too.
2) There was the idea of a stronger storm if it tracked farther south and east but again, the uncertainties regarding the more northerly track yielded some hesitation with this.
After the fact, it's always easy to go back and "Monday morning QB" but it's also great to go back and learn. Was the idea of the shear/dry air being overstated here? At the end of the day there really is no way to know that until you get to a certain point. But looking back, when Ian left Cuba with an incredible structure still intact and the eye rapidly becoming more symmetrical and the while structure becoming as organized as it did...it should have became very apparent shear/dry air was going to be a non-factor. Perhaps there was a shot dry air could have been a factor when the ERC was occurring, however, given the ERC meant little change in structure then it should have became apparent.
We've seen this with past monsters when dry air was a concern. Once a tropical system is fully mature and well organized with its structure and features it becomes very difficult to ingest the dry air. By this point the degree of rising motion and condensation is too much. There really was no way for Ian to ingest dry air into its center.
Also, I saw someone post this from Twitter but the orientation of the ULJ (despite it's strength) was one which favored enhanced upper-level divergence and probably further aided in strengthening.